BASH_BUILTINS(1) BASH_BUILTINS(1) NNAAMMEE bash, :, ., [, alias, bg, bind, break, builtin, caller, cd, command, compgen, complete, compopt, continue, declare, dirs, disown, echo, enable, eval, exec, exit, export, false, fc, fg, getopts, hash, help, history, jobs, kill, let, local, logout, mapfile, popd, printf, pushd, pwd, read, readonly, return, set, shift, shopt, source, suspend, test, times, trap, true, type, typeset, ulimit, umask, unalias, unset, wait - bash built-in commands, see bbaasshh(1) BBAASSHH BBUUIILLTTIINN CCOOMMMMAANNDDSS Unless otherwise noted, each builtin command documented in this section as accepting options preceded by -- accepts ---- to signify the end of the options. The ::, ttrruuee, ffaallssee, and tteesstt builtins do not accept options and do not treat ---- specially. The eexxiitt, llooggoouutt, bbrreeaakk, ccoonnttiinnuuee, lleett, and sshhiifftt builtins accept and process arguments beginning with -- with- out requiring ----. Other builtins that accept arguments but are not specified as accepting options interpret arguments beginning with -- as invalid options and require ---- to prevent this interpretation. :: [_a_r_g_u_m_e_n_t_s] No effect; the command does nothing beyond expanding _a_r_g_u_m_e_n_t_s and performing any specified redirections. A zero exit code is returned. .. _f_i_l_e_n_a_m_e [_a_r_g_u_m_e_n_t_s] ssoouurrccee _f_i_l_e_n_a_m_e [_a_r_g_u_m_e_n_t_s] Read and execute commands from _f_i_l_e_n_a_m_e in the current shell environment and return the exit status of the last command exe- cuted from _f_i_l_e_n_a_m_e. If _f_i_l_e_n_a_m_e does not contain a slash, file names in PPAATTHH are used to find the directory containing _f_i_l_e_- _n_a_m_e. The file searched for in PPAATTHH need not be executable. When bbaasshh is not in _p_o_s_i_x _m_o_d_e, the current directory is searched if no file is found in PPAATTHH. If the ssoouurrcceeppaatthh option to the sshhoopptt builtin command is turned off, the PPAATTHH is not searched. If any _a_r_g_u_m_e_n_t_s are supplied, they become the posi- tional parameters when _f_i_l_e_n_a_m_e is executed. Otherwise the positional parameters are unchanged. The return status is the status of the last command exited within the script (0 if no commands are executed), and false if _f_i_l_e_n_a_m_e is not found or cannot be read. aalliiaass [--pp] [_n_a_m_e[=_v_a_l_u_e] ...] AAlliiaass with no arguments or with the --pp option prints the list of aliases in the form aalliiaass _n_a_m_e=_v_a_l_u_e on standard output. When arguments are supplied, an alias is defined for each _n_a_m_e whose _v_a_l_u_e is given. A trailing space in _v_a_l_u_e causes the next word to be checked for alias substitution when the alias is expanded. For each _n_a_m_e in the argument list for which no _v_a_l_u_e is sup- plied, the name and value of the alias is printed. AAlliiaass returns true unless a _n_a_m_e is given for which no alias has been defined. bbgg [_j_o_b_s_p_e_c ...] Resume each suspended job _j_o_b_s_p_e_c in the background, as if it had been started with &&. If _j_o_b_s_p_e_c is not present, the shell's notion of the _c_u_r_r_e_n_t _j_o_b is used. bbgg _j_o_b_s_p_e_c returns 0 unless run when job control is disabled or, when run with job control enabled, any specified _j_o_b_s_p_e_c was not found or was started without job control. bbiinndd [--mm _k_e_y_m_a_p] [--llppssvvPPSSVV] bbiinndd [--mm _k_e_y_m_a_p] [--qq _f_u_n_c_t_i_o_n] [--uu _f_u_n_c_t_i_o_n] [--rr _k_e_y_s_e_q] bbiinndd [--mm _k_e_y_m_a_p] --ff _f_i_l_e_n_a_m_e bbiinndd [--mm _k_e_y_m_a_p] --xx _k_e_y_s_e_q:_s_h_e_l_l_-_c_o_m_m_a_n_d bbiinndd [--mm _k_e_y_m_a_p] _k_e_y_s_e_q:_f_u_n_c_t_i_o_n_-_n_a_m_e bbiinndd _r_e_a_d_l_i_n_e_-_c_o_m_m_a_n_d Display current rreeaaddlliinnee key and function bindings, bind a key sequence to a rreeaaddlliinnee function or macro, or set a rreeaaddlliinnee variable. Each non-option argument is a command as it would appear in _._i_n_p_u_t_r_c, but each binding or command must be passed as a separate argument; e.g., '"\C-x\C-r": re-read-init-file'. Options, if supplied, have the following meanings: --mm _k_e_y_m_a_p Use _k_e_y_m_a_p as the keymap to be affected by the subsequent bindings. Acceptable _k_e_y_m_a_p names are _e_m_a_c_s_, _e_m_a_c_s_-_s_t_a_n_- _d_a_r_d_, _e_m_a_c_s_-_m_e_t_a_, _e_m_a_c_s_-_c_t_l_x_, _v_i_, _v_i_-_m_o_v_e_, _v_i_-_c_o_m_m_a_n_d, and _v_i_-_i_n_s_e_r_t. _v_i is equivalent to _v_i_-_c_o_m_m_a_n_d; _e_m_a_c_s is equivalent to _e_m_a_c_s_-_s_t_a_n_d_a_r_d. --ll List the names of all rreeaaddlliinnee functions. --pp Display rreeaaddlliinnee function names and bindings in such a way that they can be re-read. --PP List current rreeaaddlliinnee function names and bindings. --ss Display rreeaaddlliinnee key sequences bound to macros and the strings they output in such a way that they can be re- read. --SS Display rreeaaddlliinnee key sequences bound to macros and the strings they output. --vv Display rreeaaddlliinnee variable names and values in such a way that they can be re-read. --VV List current rreeaaddlliinnee variable names and values. --ff _f_i_l_e_n_a_m_e Read key bindings from _f_i_l_e_n_a_m_e. --qq _f_u_n_c_t_i_o_n Query about which keys invoke the named _f_u_n_c_t_i_o_n. --uu _f_u_n_c_t_i_o_n Unbind all keys bound to the named _f_u_n_c_t_i_o_n. --rr _k_e_y_s_e_q Remove any current binding for _k_e_y_s_e_q. --xx _k_e_y_s_e_q::_s_h_e_l_l_-_c_o_m_m_a_n_d Cause _s_h_e_l_l_-_c_o_m_m_a_n_d to be executed whenever _k_e_y_s_e_q is entered. When _s_h_e_l_l_-_c_o_m_m_a_n_d is executed, the shell sets the RREEAADDLLIINNEE__LLIINNEE variable to the contents of the rreeaadd-- lliinnee line buffer and the RREEAADDLLIINNEE__PPOOIINNTT variable to the current location of the insertion point. If the executed command changes the value of RREEAADDLLIINNEE__LLIINNEE or RREEAADD-- LLIINNEE__PPOOIINNTT, those new values will be reflected in the editing state. The return value is 0 unless an unrecognized option is given or an error occurred. bbrreeaakk [_n] Exit from within a ffoorr, wwhhiillee, uunnttiill, or sseelleecctt loop. If _n is specified, break _n levels. _n must be >= 1. If _n is greater than the number of enclosing loops, all enclosing loops are exited. The return value is 0 unless _n is not greater than or equal to 1. bbuuiillttiinn _s_h_e_l_l_-_b_u_i_l_t_i_n [_a_r_g_u_m_e_n_t_s] Execute the specified shell builtin, passing it _a_r_g_u_m_e_n_t_s, and return its exit status. This is useful when defining a function whose name is the same as a shell builtin, retaining the func- tionality of the builtin within the function. The ccdd builtin is commonly redefined this way. The return status is false if _s_h_e_l_l_-_b_u_i_l_t_i_n is not a shell builtin command. ccaalllleerr [_e_x_p_r] Returns the context of any active subroutine call (a shell func- tion or a script executed with the .. or ssoouurrccee builtins. With- out _e_x_p_r, ccaalllleerr displays the line number and source filename of the current subroutine call. If a non-negative integer is sup- plied as _e_x_p_r, ccaalllleerr displays the line number, subroutine name, and source file corresponding to that position in the current execution call stack. This extra information may be used, for example, to print a stack trace. The current frame is frame 0. The return value is 0 unless the shell is not executing a sub- routine call or _e_x_p_r does not correspond to a valid position in the call stack. ccdd [--LL||--PP] [_d_i_r] Change the current directory to _d_i_r. The variable HHOOMMEE is the default _d_i_r. The variable CCDDPPAATTHH defines the search path for the directory containing _d_i_r. Alternative directory names in CCDDPPAATTHH are separated by a colon (:). A null directory name in CCDDPPAATTHH is the same as the current directory, i.e., ``..''. If _d_i_r begins with a slash (/), then CCDDPPAATTHH is not used. The --PP option says to use the physical directory structure instead of following symbolic links (see also the --PP option to the sseett builtin command); the --LL option forces symbolic links to be fol- lowed. An argument of -- is equivalent to $$OOLLDDPPWWDD. If a non- empty directory name from CCDDPPAATTHH is used, or if -- is the first argument, and the directory change is successful, the absolute pathname of the new working directory is written to the standard output. The return value is true if the directory was success- fully changed; false otherwise. ccoommmmaanndd [--ppVVvv] _c_o_m_m_a_n_d [_a_r_g ...] Run _c_o_m_m_a_n_d with _a_r_g_s suppressing the normal shell function lookup. Only builtin commands or commands found in the PPAATTHH are executed. If the --pp option is given, the search for _c_o_m_m_a_n_d is performed using a default value for PPAATTHH that is guaranteed to find all of the standard utilities. If either the --VV or --vv option is supplied, a description of _c_o_m_m_a_n_d is printed. The --vv option causes a single word indicating the command or file name used to invoke _c_o_m_m_a_n_d to be displayed; the --VV option produces a more verbose description. If the --VV or --vv option is supplied, the exit status is 0 if _c_o_m_m_a_n_d was found, and 1 if not. If neither option is supplied and an error occurred or _c_o_m_m_a_n_d can- not be found, the exit status is 127. Otherwise, the exit sta- tus of the ccoommmmaanndd builtin is the exit status of _c_o_m_m_a_n_d. ccoommppggeenn [_o_p_t_i_o_n] [_w_o_r_d] Generate possible completion matches for _w_o_r_d according to the _o_p_t_i_o_ns, which may be any option accepted by the ccoommpplleettee builtin with the exception of --pp and --rr, and write the matches to the standard output. When using the --FF or --CC options, the various shell variables set by the programmable completion facilities, while available, will not have useful values. The matches will be generated in the same way as if the pro- grammable completion code had generated them directly from a completion specification with the same flags. If _w_o_r_d is speci- fied, only those completions matching _w_o_r_d will be displayed. The return value is true unless an invalid option is supplied, or no matches were generated. ccoommpplleettee [--aabbccddeeffggjjkkssuuvv] [--oo _c_o_m_p_-_o_p_t_i_o_n] [--DDEE] [--AA _a_c_t_i_o_n] [--GG _g_l_o_b_- _p_a_t] [--WW _w_o_r_d_l_i_s_t] [--FF _f_u_n_c_t_i_o_n] [--CC _c_o_m_m_a_n_d] [--XX _f_i_l_t_e_r_p_a_t] [--PP _p_r_e_f_i_x] [--SS _s_u_f_f_i_x] _n_a_m_e [_n_a_m_e _._._.] ccoommpplleettee --pprr [--DDEE] [_n_a_m_e ...] Specify how arguments to each _n_a_m_e should be completed. If the --pp option is supplied, or if no options are supplied, existing completion specifications are printed in a way that allows them to be reused as input. The --rr option removes a completion spec- ification for each _n_a_m_e, or, if no _n_a_m_es are supplied, all com- pletion specifications. The --DD option indicates that the remaining options and actions should apply to the ``default'' command completion; that is, completion attempted on a command for which no completion has previously been defined. The --EE option indicates that the remaining options and actions should apply to ``empty'' command completion; that is, completion attempted on a blank line. The process of applying these completion specifications when word completion is attempted is described above under PPrroo-- ggrraammmmaabbllee CCoommpplleettiioonn. Other options, if specified, have the following meanings. The arguments to the --GG, --WW, and --XX options (and, if necessary, the --PP and --SS options) should be quoted to protect them from expan- sion before the ccoommpplleettee builtin is invoked. --oo _c_o_m_p_-_o_p_t_i_o_n The _c_o_m_p_-_o_p_t_i_o_n controls several aspects of the comp- spec's behavior beyond the simple generation of comple- tions. _c_o_m_p_-_o_p_t_i_o_n may be one of: bbaasshhddeeffaauulltt Perform the rest of the default bbaasshh completions if the compspec generates no matches. ddeeffaauulltt Use readline's default filename completion if the compspec generates no matches. ddiirrnnaammeess Perform directory name completion if the comp- spec generates no matches. ffiilleennaammeess Tell readline that the compspec generates file- names, so it can perform any filename-specific processing (like adding a slash to directory names, quoting special characters, or suppress- ing trailing spaces). Intended to be used with shell functions. nnoossppaaccee Tell readline not to append a space (the default) to words completed at the end of the line. pplluussddiirrss After any matches defined by the compspec are generated, directory name completion is attempted and any matches are added to the results of the other actions. --AA _a_c_t_i_o_n The _a_c_t_i_o_n may be one of the following to generate a list of possible completions: aalliiaass Alias names. May also be specified as --aa. aarrrraayyvvaarr Array variable names. bbiinnddiinngg RReeaaddlliinnee key binding names. bbuuiillttiinn Names of shell builtin commands. May also be specified as --bb. ccoommmmaanndd Command names. May also be specified as --cc. ddiirreeccttoorryy Directory names. May also be specified as --dd. ddiissaabblleedd Names of disabled shell builtins. eennaabblleedd Names of enabled shell builtins. eexxppoorrtt Names of exported shell variables. May also be specified as --ee. ffiillee File names. May also be specified as --ff. ffuunnccttiioonn Names of shell functions. ggrroouupp Group names. May also be specified as --gg. hheellppttooppiicc Help topics as accepted by the hheellpp builtin. hhoossttnnaammee Hostnames, as taken from the file specified by the HHOOSSTTFFIILLEE shell variable. jjoobb Job names, if job control is active. May also be specified as --jj. kkeeyywwoorrdd Shell reserved words. May also be specified as --kk. rruunnnniinngg Names of running jobs, if job control is active. sseerrvviiccee Service names. May also be specified as --ss. sseettoopptt Valid arguments for the --oo option to the sseett builtin. sshhoopptt Shell option names as accepted by the sshhoopptt builtin. ssiiggnnaall Signal names. ssttooppppeedd Names of stopped jobs, if job control is active. uusseerr User names. May also be specified as --uu. vvaarriiaabbllee Names of all shell variables. May also be spec- ified as --vv. --GG _g_l_o_b_p_a_t The pathname expansion pattern _g_l_o_b_p_a_t is expanded to generate the possible completions. --WW _w_o_r_d_l_i_s_t The _w_o_r_d_l_i_s_t is split using the characters in the IIFFSS special variable as delimiters, and each resultant word is expanded. The possible completions are the members of the resultant list which match the word being com- pleted. --CC _c_o_m_m_a_n_d _c_o_m_m_a_n_d is executed in a subshell environment, and its output is used as the possible completions. --FF _f_u_n_c_t_i_o_n The shell function _f_u_n_c_t_i_o_n is executed in the current shell environment. When it finishes, the possible com- pletions are retrieved from the value of the CCOOMMPPRREEPPLLYY array variable. --XX _f_i_l_t_e_r_p_a_t _f_i_l_t_e_r_p_a_t is a pattern as used for pathname expansion. It is applied to the list of possible completions gener- ated by the preceding options and arguments, and each completion matching _f_i_l_t_e_r_p_a_t is removed from the list. A leading !! in _f_i_l_t_e_r_p_a_t negates the pattern; in this case, any completion not matching _f_i_l_t_e_r_p_a_t is removed. --PP _p_r_e_f_i_x _p_r_e_f_i_x is added at the beginning of each possible com- pletion after all other options have been applied. --SS _s_u_f_f_i_x _s_u_f_f_i_x is appended to each possible completion after all other options have been applied. The return value is true unless an invalid option is supplied, an option other than --pp or --rr is supplied without a _n_a_m_e argu- ment, an attempt is made to remove a completion specification for a _n_a_m_e for which no specification exists, or an error occurs adding a completion specification. ccoommppoopptt [--oo _o_p_t_i_o_n] [--DDEE] [++oo _o_p_t_i_o_n] [_n_a_m_e] Modify completion options for each _n_a_m_e according to the _o_p_t_i_o_ns, or for the currently-execution completion if no _n_a_m_es are supplied. If no _o_p_t_i_o_ns are given, display the completion options for each _n_a_m_e or the current completion. The possible values of _o_p_t_i_o_n are those valid for the ccoommpplleettee builtin described above. The --DD option indicates that the remaining options should apply to the ``default'' command completion; that is, completion attempted on a command for which no completion has previously been defined. The --EE option indicates that the remaining options should apply to ``empty'' command completion; that is, completion attempted on a blank line. The return value is true unless an invalid option is supplied, an attempt is made to modify the options for a _n_a_m_e for which no comple- tion specification exists, or an output error occurs. ccoonnttiinnuuee [_n] Resume the next iteration of the enclosing ffoorr, wwhhiillee, uunnttiill, or sseelleecctt loop. If _n is specified, resume at the _nth enclosing loop. _n must be >= 1. If _n is greater than the number of enclosing loops, the last enclosing loop (the ``top-level'' loop) is resumed. The return value is 0 unless _n is not greater than or equal to 1. ddeeccllaarree [--aaAAffFFiillrrttuuxx] [--pp] [_n_a_m_e[=_v_a_l_u_e] ...] ttyyppeesseett [--aaAAffFFiillrrttuuxx] [--pp] [_n_a_m_e[=_v_a_l_u_e] ...] Declare variables and/or give them attributes. If no _n_a_m_es are given then display the values of variables. The --pp option will display the attributes and values of each _n_a_m_e. When --pp is used with _n_a_m_e arguments, additional options are ignored. When --pp is supplied without _n_a_m_e arguments, it will display the attributes and values of all variables having the attributes specified by the additional options. If no other options are supplied with --pp, ddeeccllaarree will display the attributes and values of all shell variables. The --ff option will restrict the display to shell functions. The --FF option inhibits the display of function defi- nitions; only the function name and attributes are printed. If the eexxttddeebbuugg shell option is enabled using sshhoopptt, the source file name and line number where the function is defined are dis- played as well. The --FF option implies --ff. The following options can be used to restrict output to variables with the specified attribute or to give variables attributes: --aa Each _n_a_m_e is an indexed array variable (see AArrrraayyss above). --AA Each _n_a_m_e is an associative array variable (see AArrrraayyss above). --ff Use function names only. --ii The variable is treated as an integer; arithmetic evalua- tion (see AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN above) is performed when the variable is assigned a value. --ll When the variable is assigned a value, all upper-case characters are converted to lower-case. The upper-case attribute is disabled. --rr Make _n_a_m_es readonly. These names cannot then be assigned values by subsequent assignment statements or unset. --tt Give each _n_a_m_e the _t_r_a_c_e attribute. Traced functions inherit the DDEEBBUUGG and RREETTUURRNN traps from the calling shell. The trace attribute has no special meaning for variables. --uu When the variable is assigned a value, all lower-case characters are converted to upper-case. The lower-case attribute is disabled. --xx Mark _n_a_m_es for export to subsequent commands via the environment. Using `+' instead of `-' turns off the attribute instead, with the exceptions that ++aa may not be used to destroy an array vari- able and ++rr will not remove the readonly attribute. When used in a function, makes each _n_a_m_e local, as with the llooccaall command. If a variable name is followed by =_v_a_l_u_e, the value of the vari- able is set to _v_a_l_u_e. The return value is 0 unless an invalid option is encountered, an attempt is made to define a function using ``-f foo=bar'', an attempt is made to assign a value to a readonly variable, an attempt is made to assign a value to an array variable without using the compound assignment syntax (see AArrrraayyss above), one of the _n_a_m_e_s is not a valid shell variable name, an attempt is made to turn off readonly status for a read- only variable, an attempt is made to turn off array status for an array variable, or an attempt is made to display a non-exis- tent function with --ff. ddiirrss [[++_n]] [[--_n]] [[--ccppllvv]] Without options, displays the list of currently remembered directories. The default display is on a single line with directory names separated by spaces. Directories are added to the list with the ppuusshhdd command; the ppooppdd command removes entries from the list. ++_n Displays the _nth entry counting from the left of the list shown by ddiirrss when invoked without options, starting with zero. --_n Displays the _nth entry counting from the right of the list shown by ddiirrss when invoked without options, starting with zero. --cc Clears the directory stack by deleting all of the entries. --ll Produces a longer listing; the default listing format uses a tilde to denote the home directory. --pp Print the directory stack with one entry per line. --vv Print the directory stack with one entry per line, pre- fixing each entry with its index in the stack. The return value is 0 unless an invalid option is supplied or _n indexes beyond the end of the directory stack. ddiissoowwnn [--aarr] [--hh] [_j_o_b_s_p_e_c ...] Without options, each _j_o_b_s_p_e_c is removed from the table of active jobs. If _j_o_b_s_p_e_c is not present, and neither --aa nor --rr is supplied, the shell's notion of the _c_u_r_r_e_n_t _j_o_b is used. If the --hh option is given, each _j_o_b_s_p_e_c is not removed from the ta- ble, but is marked so that SSIIGGHHUUPP is not sent to the job if the shell receives a SSIIGGHHUUPP. If no _j_o_b_s_p_e_c is present, and neither the --aa nor the --rr option is supplied, the _c_u_r_r_e_n_t _j_o_b is used. If no _j_o_b_s_p_e_c is supplied, the --aa option means to remove or mark all jobs; the --rr option without a _j_o_b_s_p_e_c argument restricts operation to running jobs. The return value is 0 unless a _j_o_b_- _s_p_e_c does not specify a valid job. eecchhoo [--nneeEE] [_a_r_g ...] Output the _a_r_gs, separated by spaces, followed by a newline. The return status is always 0. If --nn is specified, the trailing newline is suppressed. If the --ee option is given, interpreta- tion of the following backslash-escaped characters is enabled. The --EE option disables the interpretation of these escape char- acters, even on systems where they are interpreted by default. The xxppgg__eecchhoo shell option may be used to dynamically determine whether or not eecchhoo expands these escape characters by default. eecchhoo does not interpret ---- to mean the end of options. eecchhoo interprets the following escape sequences: \\aa alert (bell) \\bb backspace \\cc suppress further output \\ee an escape character \\ff form feed \\nn new line \\rr carriage return \\tt horizontal tab \\vv vertical tab \\\\ backslash \\00_n_n_n the eight-bit character whose value is the octal value _n_n_n (zero to three octal digits) \\xx_H_H the eight-bit character whose value is the hexadecimal value _H_H (one or two hex digits) eennaabbllee [--aa] [--ddnnppss] [--ff _f_i_l_e_n_a_m_e] [_n_a_m_e ...] Enable and disable builtin shell commands. Disabling a builtin allows a disk command which has the same name as a shell builtin to be executed without specifying a full pathname, even though the shell normally searches for builtins before disk commands. If --nn is used, each _n_a_m_e is disabled; otherwise, _n_a_m_e_s are enabled. For example, to use the tteesstt binary found via the PPAATTHH instead of the shell builtin version, run ``enable -n test''. The --ff option means to load the new builtin command _n_a_m_e from shared object _f_i_l_e_n_a_m_e, on systems that support dynamic loading. The --dd option will delete a builtin previously loaded with --ff. If no _n_a_m_e arguments are given, or if the --pp option is supplied, a list of shell builtins is printed. With no other option argu- ments, the list consists of all enabled shell builtins. If --nn is supplied, only disabled builtins are printed. If --aa is sup- plied, the list printed includes all builtins, with an indica- tion of whether or not each is enabled. If --ss is supplied, the output is restricted to the POSIX _s_p_e_c_i_a_l builtins. The return value is 0 unless a _n_a_m_e is not a shell builtin or there is an error loading a new builtin from a shared object. eevvaall [_a_r_g ...] The _a_r_gs are read and concatenated together into a single com- mand. This command is then read and executed by the shell, and its exit status is returned as the value of eevvaall. If there are no _a_r_g_s, or only null arguments, eevvaall returns 0. eexxeecc [--ccll] [--aa _n_a_m_e] [_c_o_m_m_a_n_d [_a_r_g_u_m_e_n_t_s]] If _c_o_m_m_a_n_d is specified, it replaces the shell. No new process is created. The _a_r_g_u_m_e_n_t_s become the arguments to _c_o_m_m_a_n_d. If the --ll option is supplied, the shell places a dash at the begin- ning of the zeroth argument passed to _c_o_m_m_a_n_d. This is what _l_o_g_i_n(1) does. The --cc option causes _c_o_m_m_a_n_d to be executed with an empty environment. If --aa is supplied, the shell passes _n_a_m_e as the zeroth argument to the executed command. If _c_o_m_m_a_n_d can- not be executed for some reason, a non-interactive shell exits, unless the shell option eexxeeccffaaiill is enabled, in which case it returns failure. An interactive shell returns failure if the file cannot be executed. If _c_o_m_m_a_n_d is not specified, any redi- rections take effect in the current shell, and the return status is 0. If there is a redirection error, the return status is 1. eexxiitt [_n] Cause the shell to exit with a status of _n. If _n is omitted, the exit status is that of the last command executed. A trap on EEXXIITT is executed before the shell terminates. eexxppoorrtt [--ffnn] [_n_a_m_e[=_w_o_r_d]] ... eexxppoorrtt --pp The supplied _n_a_m_e_s are marked for automatic export to the envi- ronment of subsequently executed commands. If the --ff option is given, the _n_a_m_e_s refer to functions. If no _n_a_m_e_s are given, or if the --pp option is supplied, a list of all names that are exported in this shell is printed. The --nn option causes the export property to be removed from each _n_a_m_e. If a variable name is followed by =_w_o_r_d, the value of the variable is set to _w_o_r_d. eexxppoorrtt returns an exit status of 0 unless an invalid option is encountered, one of the _n_a_m_e_s is not a valid shell variable name, or --ff is supplied with a _n_a_m_e that is not a func- tion. ffcc [--ee _e_n_a_m_e] [--llnnrr] [_f_i_r_s_t] [_l_a_s_t] ffcc --ss [_p_a_t=_r_e_p] [_c_m_d] Fix Command. In the first form, a range of commands from _f_i_r_s_t to _l_a_s_t is selected from the history list. _F_i_r_s_t and _l_a_s_t may be specified as a string (to locate the last command beginning with that string) or as a number (an index into the history list, where a negative number is used as an offset from the cur- rent command number). If _l_a_s_t is not specified it is set to the current command for listing (so that ``fc -l -10'' prints the last 10 commands) and to _f_i_r_s_t otherwise. If _f_i_r_s_t is not spec- ified it is set to the previous command for editing and -16 for listing. The --nn option suppresses the command numbers when listing. The --rr option reverses the order of the commands. If the --ll option is given, the commands are listed on standard output. Other- wise, the editor given by _e_n_a_m_e is invoked on a file containing those commands. If _e_n_a_m_e is not given, the value of the FFCCEEDDIITT variable is used, and the value of EEDDIITTOORR if FFCCEEDDIITT is not set. If neither variable is set, is used. When editing is complete, the edited commands are echoed and executed. In the second form, _c_o_m_m_a_n_d is re-executed after each instance of _p_a_t is replaced by _r_e_p. A useful alias to use with this is ``r="fc -s"'', so that typing ``r cc'' runs the last command beginning with ``cc'' and typing ``r'' re-executes the last com- mand. If the first form is used, the return value is 0 unless an invalid option is encountered or _f_i_r_s_t or _l_a_s_t specify history lines out of range. If the --ee option is supplied, the return value is the value of the last command executed or failure if an error occurs with the temporary file of commands. If the second form is used, the return status is that of the command re-exe- cuted, unless _c_m_d does not specify a valid history line, in which case ffcc returns failure. ffgg [_j_o_b_s_p_e_c] Resume _j_o_b_s_p_e_c in the foreground, and make it the current job. If _j_o_b_s_p_e_c is not present, the shell's notion of the _c_u_r_r_e_n_t _j_o_b is used. The return value is that of the command placed into the foreground, or failure if run when job control is disabled or, when run with job control enabled, if _j_o_b_s_p_e_c does not spec- ify a valid job or _j_o_b_s_p_e_c specifies a job that was started without job control. ggeettooppttss _o_p_t_s_t_r_i_n_g _n_a_m_e [_a_r_g_s] ggeettooppttss is used by shell procedures to parse positional parame- ters. _o_p_t_s_t_r_i_n_g contains the option characters to be recog- nized; if a character is followed by a colon, the option is expected to have an argument, which should be separated from it by white space. The colon and question mark characters may not be used as option characters. Each time it is invoked, ggeettooppttss places the next option in the shell variable _n_a_m_e, initializing _n_a_m_e if it does not exist, and the index of the next argument to be processed into the variable OOPPTTIINNDD. OOPPTTIINNDD is initialized to 1 each time the shell or a shell script is invoked. When an option requires an argument, ggeettooppttss places that argument into the variable OOPPTTAARRGG. The shell does not reset OOPPTTIINNDD automati- cally; it must be manually reset between multiple calls to ggeettooppttss within the same shell invocation if a new set of parame- ters is to be used. When the end of options is encountered, ggeettooppttss exits with a return value greater than zero. OOPPTTIINNDD is set to the index of the first non-option argument, and nnaammee is set to ?. ggeettooppttss normally parses the positional parameters, but if more arguments are given in _a_r_g_s, ggeettooppttss parses those instead. ggeettooppttss can report errors in two ways. If the first character of _o_p_t_s_t_r_i_n_g is a colon, _s_i_l_e_n_t error reporting is used. In normal operation diagnostic messages are printed when invalid options or missing option arguments are encountered. If the variable OOPPTTEERRRR is set to 0, no error messages will be dis- played, even if the first character of _o_p_t_s_t_r_i_n_g is not a colon. If an invalid option is seen, ggeettooppttss places ? into _n_a_m_e and, if not silent, prints an error message and unsets OOPPTTAARRGG. If ggeettooppttss is silent, the option character found is placed in OOPPTTAARRGG and no diagnostic message is printed. If a required argument is not found, and ggeettooppttss is not silent, a question mark (??) is placed in _n_a_m_e, OOPPTTAARRGG is unset, and a diagnostic message is printed. If ggeettooppttss is silent, then a colon (::) is placed in _n_a_m_e and OOPPTTAARRGG is set to the option character found. ggeettooppttss returns true if an option, specified or unspecified, is found. It returns false if the end of options is encountered or an error occurs. hhaasshh [--llrr] [--pp _f_i_l_e_n_a_m_e] [--ddtt] [_n_a_m_e] For each _n_a_m_e, the full file name of the command is determined by searching the directories in $$PPAATTHH and remembered. If the --pp option is supplied, no path search is performed, and _f_i_l_e_n_a_m_e is used as the full file name of the command. The --rr option causes the shell to forget all remembered locations. The --dd option causes the shell to forget the remembered location of each _n_a_m_e. If the --tt option is supplied, the full pathname to which each _n_a_m_e corresponds is printed. If multiple _n_a_m_e arguments are supplied with --tt, the _n_a_m_e is printed before the hashed full pathname. The --ll option causes output to be displayed in a for- mat that may be reused as input. If no arguments are given, or if only --ll is supplied, information about remembered commands is printed. The return status is true unless a _n_a_m_e is not found or an invalid option is supplied. hheellpp [--ddmmss] [_p_a_t_t_e_r_n] Display helpful information about builtin commands. If _p_a_t_t_e_r_n is specified, hheellpp gives detailed help on all commands matching _p_a_t_t_e_r_n; otherwise help for all the builtins and shell control structures is printed. --dd Display a short description of each _p_a_t_t_e_r_n --mm Display the description of each _p_a_t_t_e_r_n in a manpage-like format --ss Display only a short usage synopsis for each _p_a_t_t_e_r_n The return status is 0 unless no command matches _p_a_t_t_e_r_n. hhiissttoorryy [[_n]] hhiissttoorryy --cc hhiissttoorryy --dd _o_f_f_s_e_t hhiissttoorryy --aannrrww [_f_i_l_e_n_a_m_e] hhiissttoorryy --pp _a_r_g [_a_r_g _._._.] hhiissttoorryy --ss _a_r_g [_a_r_g _._._.] With no options, display the command history list with line num- bers. Lines listed with a ** have been modified. An argument of _n lists only the last _n lines. If the shell variable HHIISSTTTTIIMMEE-- FFOORRMMAATT is set and not null, it is used as a format string for _s_t_r_f_t_i_m_e(3) to display the time stamp associated with each dis- played history entry. No intervening blank is printed between the formatted time stamp and the history line. If _f_i_l_e_n_a_m_e is supplied, it is used as the name of the history file; if not, the value of HHIISSTTFFIILLEE is used. Options, if supplied, have the following meanings: --cc Clear the history list by deleting all the entries. --dd _o_f_f_s_e_t Delete the history entry at position _o_f_f_s_e_t. --aa Append the ``new'' history lines (history lines entered since the beginning of the current bbaasshh session) to the history file. --nn Read the history lines not already read from the history file into the current history list. These are lines appended to the history file since the beginning of the current bbaasshh session. --rr Read the contents of the history file and use them as the current history. --ww Write the current history to the history file, overwrit- ing the history file's contents. --pp Perform history substitution on the following _a_r_g_s and display the result on the standard output. Does not store the results in the history list. Each _a_r_g must be quoted to disable normal history expansion. --ss Store the _a_r_g_s in the history list as a single entry. The last command in the history list is removed before the _a_r_g_s are added. If the HHIISSTTTTIIMMEEFFOORRMMAATT variable is set, the time stamp informa- tion associated with each history entry is written to the his- tory file, marked with the history comment character. When the history file is read, lines beginning with the history comment character followed immediately by a digit are interpreted as timestamps for the previous history line. The return value is 0 unless an invalid option is encountered, an error occurs while reading or writing the history file, an invalid _o_f_f_s_e_t is sup- plied as an argument to --dd, or the history expansion supplied as an argument to --pp fails. jjoobbss [--llnnpprrss] [ _j_o_b_s_p_e_c ... ] jjoobbss --xx _c_o_m_m_a_n_d [ _a_r_g_s ... ] The first form lists the active jobs. The options have the fol- lowing meanings: --ll List process IDs in addition to the normal information. --pp List only the process ID of the job's process group leader. --nn Display information only about jobs that have changed status since the user was last notified of their status. --rr Restrict output to running jobs. --ss Restrict output to stopped jobs. If _j_o_b_s_p_e_c is given, output is restricted to information about that job. The return status is 0 unless an invalid option is encountered or an invalid _j_o_b_s_p_e_c is supplied. If the --xx option is supplied, jjoobbss replaces any _j_o_b_s_p_e_c found in _c_o_m_m_a_n_d or _a_r_g_s with the corresponding process group ID, and executes _c_o_m_m_a_n_d passing it _a_r_g_s, returning its exit status. kkiillll [--ss _s_i_g_s_p_e_c | --nn _s_i_g_n_u_m | --_s_i_g_s_p_e_c] [_p_i_d | _j_o_b_s_p_e_c] ... kkiillll --ll [_s_i_g_s_p_e_c | _e_x_i_t___s_t_a_t_u_s] Send the signal named by _s_i_g_s_p_e_c or _s_i_g_n_u_m to the processes named by _p_i_d or _j_o_b_s_p_e_c. _s_i_g_s_p_e_c is either a case-insensitive signal name such as SSIIGGKKIILLLL (with or without the SSIIGG prefix) or a signal number; _s_i_g_n_u_m is a signal number. If _s_i_g_s_p_e_c is not present, then SSIIGGTTEERRMM is assumed. An argument of --ll lists the signal names. If any arguments are supplied when --ll is given, the names of the signals corresponding to the arguments are listed, and the return status is 0. The _e_x_i_t___s_t_a_t_u_s argument to --ll is a number specifying either a signal number or the exit status of a process terminated by a signal. kkiillll returns true if at least one signal was successfully sent, or false if an error occurs or an invalid option is encountered. lleett _a_r_g [_a_r_g ...] Each _a_r_g is an arithmetic expression to be evaluated (see AARRIITTHH-- MMEETTIICC EEVVAALLUUAATTIIOONN above). If the last _a_r_g evaluates to 0, lleett returns 1; 0 is returned otherwise. llooccaall [_o_p_t_i_o_n] [_n_a_m_e[=_v_a_l_u_e] ...] For each argument, a local variable named _n_a_m_e is created, and assigned _v_a_l_u_e. The _o_p_t_i_o_n can be any of the options accepted by ddeeccllaarree. When llooccaall is used within a function, it causes the variable _n_a_m_e to have a visible scope restricted to that func- tion and its children. With no operands, llooccaall writes a list of local variables to the standard output. It is an error to use llooccaall when not within a function. The return status is 0 unless llooccaall is used outside a function, an invalid _n_a_m_e is supplied, or _n_a_m_e is a readonly variable. llooggoouutt Exit a login shell. mmaappffiillee [--nn _c_o_u_n_t] [--OO _o_r_i_g_i_n] [--ss _c_o_u_n_t] [--tt] [--uu _f_d] [--CC _c_a_l_l_b_a_c_k] [--cc _q_u_a_n_t_u_m] [_a_r_r_a_y] rreeaaddaarrrraayy [--nn _c_o_u_n_t] [--OO _o_r_i_g_i_n] [--ss _c_o_u_n_t] [--tt] [--uu _f_d] [--CC _c_a_l_l_b_a_c_k] [--cc _q_u_a_n_t_u_m] [_a_r_r_a_y] Read lines from the standard input into the indexed array vari- able _a_r_r_a_y, or from file descriptor _f_d if the --uu option is sup- plied. The variable MMAAPPFFIILLEE is the default _a_r_r_a_y. Options, if supplied, have the following meanings: --nn Copy at most _c_o_u_n_t lines. If _c_o_u_n_t is 0, all lines are copied. --OO Begin assigning to _a_r_r_a_y at index _o_r_i_g_i_n. The default index is 0. --ss Discard the first _c_o_u_n_t lines read. --tt Remove a trailing newline from each line read. --uu Read lines from file descriptor _f_d instead of the stan- dard input. --CC Evaluate _c_a_l_l_b_a_c_k each time _q_u_a_n_t_u_m lines are read. The --cc option specifies _q_u_a_n_t_u_m. --cc Specify the number of lines read between each call to _c_a_l_l_b_a_c_k. If --CC is specified without --cc, the default quantum is 5000. When _c_a_l_l_b_a_c_k is evaluated, it is supplied the index of the next array element to be assigned as an additional argument. _c_a_l_l_- _b_a_c_k is evaluated after the line is read but before the array element is assigned. If not supplied with an explicit origin, mmaappffiillee will clear _a_r_r_a_y before assigning to it. mmaappffiillee returns successfully unless an invalid option or option argument is supplied, _a_r_r_a_y is invalid or unassignable, or if _a_r_r_a_y is not an indexed array. ppooppdd [-nn] [+_n] [-_n] Removes entries from the directory stack. With no arguments, removes the top directory from the stack, and performs a ccdd to the new top directory. Arguments, if supplied, have the follow- ing meanings: --nn Suppresses the normal change of directory when removing directories from the stack, so that only the stack is manipulated. ++_n Removes the _nth entry counting from the left of the list shown by ddiirrss, starting with zero. For example: ``popd +0'' removes the first directory, ``popd +1'' the second. --_n Removes the _nth entry counting from the right of the list shown by ddiirrss, starting with zero. For example: ``popd -0'' removes the last directory, ``popd -1'' the next to last. If the ppooppdd command is successful, a ddiirrss is performed as well, and the return status is 0. ppooppdd returns false if an invalid option is encountered, the directory stack is empty, a non-exis- tent directory stack entry is specified, or the directory change fails. pprriinnttff [--vv _v_a_r] _f_o_r_m_a_t [_a_r_g_u_m_e_n_t_s] Write the formatted _a_r_g_u_m_e_n_t_s to the standard output under the control of the _f_o_r_m_a_t. The _f_o_r_m_a_t is a character string which contains three types of objects: plain characters, which are simply copied to standard output, character escape sequences, which are converted and copied to the standard output, and for- mat specifications, each of which causes printing of the next successive _a_r_g_u_m_e_n_t. In addition to the standard _p_r_i_n_t_f(1) for- mats, %%bb causes pprriinnttff to expand backslash escape sequences in the corresponding _a_r_g_u_m_e_n_t (except that \\cc terminates output, backslashes in \\'', \\"", and \\?? are not removed, and octal escapes beginning with \\00 may contain up to four digits), and %%qq causes pprriinnttff to output the corresponding _a_r_g_u_m_e_n_t in a format that can be reused as shell input. The --vv option causes the output to be assigned to the variable _v_a_r rather than being printed to the standard output. The _f_o_r_m_a_t is reused as necessary to consume all of the _a_r_g_u_- _m_e_n_t_s. If the _f_o_r_m_a_t requires more _a_r_g_u_m_e_n_t_s than are supplied, the extra format specifications behave as if a zero value or null string, as appropriate, had been supplied. The return value is zero on success, non-zero on failure. ppuusshhdd [--nn] [+_n] [-_n] ppuusshhdd [--nn] [_d_i_r] Adds a directory to the top of the directory stack, or rotates the stack, making the new top of the stack the current working directory. With no arguments, exchanges the top two directories and returns 0, unless the directory stack is empty. Arguments, if supplied, have the following meanings: --nn Suppresses the normal change of directory when adding directories to the stack, so that only the stack is manipulated. ++_n Rotates the stack so that the _nth directory (counting from the left of the list shown by ddiirrss, starting with zero) is at the top. --_n Rotates the stack so that the _nth directory (counting from the right of the list shown by ddiirrss, starting with zero) is at the top. _d_i_r Adds _d_i_r to the directory stack at the top, making it the new current working directory. If the ppuusshhdd command is successful, a ddiirrss is performed as well. If the first form is used, ppuusshhdd returns 0 unless the cd to _d_i_r fails. With the second form, ppuusshhdd returns 0 unless the direc- tory stack is empty, a non-existent directory stack element is specified, or the directory change to the specified new current directory fails. ppwwdd [--LLPP] Print the absolute pathname of the current working directory. The pathname printed contains no symbolic links if the --PP option is supplied or the --oo pphhyyssiiccaall option to the sseett builtin command is enabled. If the --LL option is used, the pathname printed may contain symbolic links. The return status is 0 unless an error occurs while reading the name of the current directory or an invalid option is supplied. rreeaadd [--eerrss] [--aa _a_n_a_m_e] [--dd _d_e_l_i_m] [--ii _t_e_x_t] [--nn _n_c_h_a_r_s] [--NN _n_c_h_a_r_s] [--pp _p_r_o_m_p_t] [--tt _t_i_m_e_o_u_t] [--uu _f_d] [_n_a_m_e ...] One line is read from the standard input, or from the file descriptor _f_d supplied as an argument to the --uu option, and the first word is assigned to the first _n_a_m_e, the second word to the second _n_a_m_e, and so on, with leftover words and their interven- ing separators assigned to the last _n_a_m_e. If there are fewer words read from the input stream than names, the remaining names are assigned empty values. The characters in IIFFSS are used to split the line into words. The backslash character (\\) may be used to remove any special meaning for the next character read and for line continuation. Options, if supplied, have the fol- lowing meanings: --aa _a_n_a_m_e The words are assigned to sequential indices of the array variable _a_n_a_m_e, starting at 0. _a_n_a_m_e is unset before any new values are assigned. Other _n_a_m_e arguments are ignored. --dd _d_e_l_i_m The first character of _d_e_l_i_m is used to terminate the input line, rather than newline. --ee If the standard input is coming from a terminal, rreeaaddlliinnee (see RREEAADDLLIINNEE above) is used to obtain the line. Read- line uses the current (or default, if line editing was not previously active) editing settings. --ii _t_e_x_t If rreeaaddlliinnee is being used to read the line, _t_e_x_t is placed into the editing buffer before editing begins. --nn _n_c_h_a_r_s rreeaadd returns after reading _n_c_h_a_r_s characters rather than waiting for a complete line of input, but honor a delim- iter if fewer than _n_c_h_a_r_s characters are read before the delimiter. --NN _n_c_h_a_r_s rreeaadd returns after reading exactly _n_c_h_a_r_s characters rather than waiting for a complete line of input, unless EOF is encountered or rreeaadd times out. Delimiter charac- ters encountered in the input are not treated specially and do not cause rreeaadd to return until _n_c_h_a_r_s characters are read. --pp _p_r_o_m_p_t Display _p_r_o_m_p_t on standard error, without a trailing new- line, before attempting to read any input. The prompt is displayed only if input is coming from a terminal. --rr Backslash does not act as an escape character. The back- slash is considered to be part of the line. In particu- lar, a backslash-newline pair may not be used as a line continuation. --ss Silent mode. If input is coming from a terminal, charac- ters are not echoed. --tt _t_i_m_e_o_u_t Cause rreeaadd to time out and return failure if a complete line of input is not read within _t_i_m_e_o_u_t seconds. _t_i_m_e_- _o_u_t may be a decimal number with a fractional portion following the decimal point. This option is only effec- tive if rreeaadd is reading input from a terminal, pipe, or other special file; it has no effect when reading from regular files. If _t_i_m_e_o_u_t is 0, rreeaadd returns success if input is available on the specified file descriptor, failure otherwise. The exit status is greater than 128 if the timeout is exceeded. --uu _f_d Read input from file descriptor _f_d. If no _n_a_m_e_s are supplied, the line read is assigned to the vari- able RREEPPLLYY. The return code is zero, unless end-of-file is encountered, rreeaadd times out (in which case the return code is greater than 128), or an invalid file descriptor is supplied as the argument to --uu. rreeaaddoonnllyy [--aaAAppff] [_n_a_m_e[=_w_o_r_d] ...] The given _n_a_m_e_s are marked readonly; the values of these _n_a_m_e_s may not be changed by subsequent assignment. If the --ff option is supplied, the functions corresponding to the _n_a_m_e_s are so marked. The --aa option restricts the variables to indexed arrays; the --AA option restricts the variables to associative arrays. If no _n_a_m_e arguments are given, or if the --pp option is supplied, a list of all readonly names is printed. The --pp option causes output to be displayed in a format that may be reused as input. If a variable name is followed by =_w_o_r_d, the value of the variable is set to _w_o_r_d. The return status is 0 unless an invalid option is encountered, one of the _n_a_m_e_s is not a valid shell variable name, or --ff is supplied with a _n_a_m_e that is not a function. rreettuurrnn [_n] Causes a function to exit with the return value specified by _n. If _n is omitted, the return status is that of the last command executed in the function body. If used outside a function, but during execution of a script by the .. (ssoouurrccee) command, it causes the shell to stop executing that script and return either _n or the exit status of the last command executed within the script as the exit status of the script. If used outside a function and not during execution of a script by .., the return status is false. Any command associated with the RREETTUURRNN trap is executed before execution resumes after the function or script. sseett [----aabbeeffhhkkmmnnppttuuvvxxBBCCEEHHPPTT] [--oo _o_p_t_i_o_n] [_a_r_g ...] sseett [++aabbeeffhhkkmmnnppttuuvvxxBBCCEEHHPPTT] [++oo _o_p_t_i_o_n] [_a_r_g ...] Without options, the name and value of each shell variable are displayed in a format that can be reused as input for setting or resetting the currently-set variables. Read-only variables can- not be reset. In _p_o_s_i_x _m_o_d_e, only shell variables are listed. The output is sorted according to the current locale. When options are specified, they set or unset shell attributes. Any arguments remaining after option processing are treated as val- ues for the positional parameters and are assigned, in order, to $$11, $$22, ...... $$_n. Options, if specified, have the following meanings: --aa Automatically mark variables and functions which are modified or created for export to the environment of subsequent commands. --bb Report the status of terminated background jobs immedi- ately, rather than before the next primary prompt. This is effective only when job control is enabled. --ee Exit immediately if a _p_i_p_e_l_i_n_e (which may consist of a single _s_i_m_p_l_e _c_o_m_m_a_n_d), a _s_u_b_s_h_e_l_l command enclosed in parentheses, or one of the commands executed as part of a command list enclosed by braces (see SSHHEELLLL GGRRAAMMMMAARR above) exits with a non-zero status. The shell does not exit if the command that fails is part of the command list immediately following a wwhhiillee or uunnttiill keyword, part of the test following the iiff or eelliiff reserved words, part of any command executed in a &&&& or |||| list except the command following the final &&&& or ||||, any command in a pipeline but the last, or if the command's return value is being inverted with !!. A trap on EERRRR, if set, is executed before the shell exits. This option applies to the shell environment and each subshell envi- ronment separately (see CCOOMMMMAANNDD EEXXEECCUUTTIIOONN EENNVVIIRROONNMMEENNTT above), and may cause subshells to exit before executing all the commands in the subshell. --ff Disable pathname expansion. --hh Remember the location of commands as they are looked up for execution. This is enabled by default. --kk All arguments in the form of assignment statements are placed in the environment for a command, not just those that precede the command name. --mm Monitor mode. Job control is enabled. This option is on by default for interactive shells on systems that support it (see JJOOBB CCOONNTTRROOLL above). Background pro- cesses run in a separate process group and a line con- taining their exit status is printed upon their comple- tion. --nn Read commands but do not execute them. This may be used to check a shell script for syntax errors. This is ignored by interactive shells. --oo _o_p_t_i_o_n_-_n_a_m_e The _o_p_t_i_o_n_-_n_a_m_e can be one of the following: aalllleexxppoorrtt Same as --aa. bbrraacceeeexxppaanndd Same as --BB. eemmaaccss Use an emacs-style command line editing inter- face. This is enabled by default when the shell is interactive, unless the shell is started with the ----nnooeeddiittiinngg option. This also affects the editing interface used for rreeaadd --ee. eerrrreexxiitt Same as --ee. eerrrrttrraaccee Same as --EE. ffuunnccttrraaccee Same as --TT. hhaasshhaallll Same as --hh. hhiisstteexxppaanndd Same as --HH. hhiissttoorryy Enable command history, as described above under HHIISSTTOORRYY. This option is on by default in inter- active shells. iiggnnoorreeeeooff The effect is as if the shell command ``IGNOREEOF=10'' had been executed (see SShheellll VVaarriiaabblleess above). kkeeyywwoorrdd Same as --kk. mmoonniittoorr Same as --mm. nnoocclloobbbbeerr Same as --CC. nnooeexxeecc Same as --nn. nnoogglloobb Same as --ff. nnoolloogg Currently ignored. nnoottiiffyy Same as --bb. nnoouunnsseett Same as --uu. oonneeccmmdd Same as --tt. pphhyyssiiccaall Same as --PP. ppiippeeffaaiill If set, the return value of a pipeline is the value of the last (rightmost) command to exit with a non-zero status, or zero if all commands in the pipeline exit successfully. This option is disabled by default. ppoossiixx Change the behavior of bbaasshh where the default operation differs from the POSIX standard to match the standard (_p_o_s_i_x _m_o_d_e). pprriivviilleeggeedd Same as --pp. vveerrbboossee Same as --vv. vvii Use a vi-style command line editing interface. This also affects the editing interface used for rreeaadd --ee. xxttrraaccee Same as --xx. If --oo is supplied with no _o_p_t_i_o_n_-_n_a_m_e, the values of the current options are printed. If ++oo is supplied with no _o_p_t_i_o_n_-_n_a_m_e, a series of sseett commands to recreate the current option settings is displayed on the standard output. --pp Turn on _p_r_i_v_i_l_e_g_e_d mode. In this mode, the $$EENNVV and $$BBAASSHH__EENNVV files are not processed, shell functions are not inherited from the environment, and the SSHHEELLLLOOPPTTSS, BBAASSHHOOPPTTSS, CCDDPPAATTHH, and GGLLOOBBIIGGNNOORREE variables, if they appear in the environment, are ignored. If the shell is started with the effective user (group) id not equal to the real user (group) id, and the --pp option is not sup- plied, these actions are taken and the effective user id is set to the real user id. If the --pp option is sup- plied at startup, the effective user id is not reset. Turning this option off causes the effective user and group ids to be set to the real user and group ids. --tt Exit after reading and executing one command. --uu Treat unset variables and parameters other than the spe- cial parameters "@" and "*" as an error when performing parameter expansion. If expansion is attempted on an unset variable or parameter, the shell prints an error message, and, if not interactive, exits with a non-zero status. --vv Print shell input lines as they are read. --xx After expanding each _s_i_m_p_l_e _c_o_m_m_a_n_d, ffoorr command, ccaassee command, sseelleecctt command, or arithmetic ffoorr command, dis- play the expanded value of PPSS44, followed by the command and its expanded arguments or associated word list. --BB The shell performs brace expansion (see BBrraaccee EExxppaannssiioonn above). This is on by default. --CC If set, bbaasshh does not overwrite an existing file with the >>, >>&&, and <<>> redirection operators. This may be overridden when creating output files by using the redi- rection operator >>|| instead of >>. --EE If set, any trap on EERRRR is inherited by shell functions, command substitutions, and commands executed in a sub- shell environment. The EERRRR trap is normally not inher- ited in such cases. --HH Enable !! style history substitution. This option is on by default when the shell is interactive. --PP If set, the shell does not follow symbolic links when executing commands such as ccdd that change the current working directory. It uses the physical directory structure instead. By default, bbaasshh follows the logical chain of directories when performing commands which change the current directory. --TT If set, any traps on DDEEBBUUGG and RREETTUURRNN are inherited by shell functions, command substitutions, and commands executed in a subshell environment. The DDEEBBUUGG and RREETTUURRNN traps are normally not inherited in such cases. ---- If no arguments follow this option, then the positional parameters are unset. Otherwise, the positional parame- ters are set to the _a_r_gs, even if some of them begin with a --. -- Signal the end of options, cause all remaining _a_r_gs to be assigned to the positional parameters. The --xx and --vv options are turned off. If there are no _a_r_gs, the posi- tional parameters remain unchanged. The options are off by default unless otherwise noted. Using + rather than - causes these options to be turned off. The options can also be specified as arguments to an invocation of the shell. The current set of options may be found in $$--. The return status is always true unless an invalid option is encoun- tered. sshhiifftt [_n] The positional parameters from _n+1 ... are renamed to $$11 ........ Parameters represented by the numbers $$## down to $$##-_n+1 are unset. _n must be a non-negative number less than or equal to $$##. If _n is 0, no parameters are changed. If _n is not given, it is assumed to be 1. If _n is greater than $$##, the positional parameters are not changed. The return status is greater than zero if _n is greater than $$## or less than zero; otherwise 0. sshhoopptt [--ppqqssuu] [--oo] [_o_p_t_n_a_m_e ...] Toggle the values of variables controlling optional shell behav- ior. With no options, or with the --pp option, a list of all set- table options is displayed, with an indication of whether or not each is set. The --pp option causes output to be displayed in a form that may be reused as input. Other options have the fol- lowing meanings: --ss Enable (set) each _o_p_t_n_a_m_e. --uu Disable (unset) each _o_p_t_n_a_m_e. --qq Suppresses normal output (quiet mode); the return status indicates whether the _o_p_t_n_a_m_e is set or unset. If multi- ple _o_p_t_n_a_m_e arguments are given with --qq, the return sta- tus is zero if all _o_p_t_n_a_m_e_s are enabled; non-zero other- wise. --oo Restricts the values of _o_p_t_n_a_m_e to be those defined for the --oo option to the sseett builtin. If either --ss or --uu is used with no _o_p_t_n_a_m_e arguments, the dis- play is limited to those options which are set or unset, respec- tively. Unless otherwise noted, the sshhoopptt options are disabled (unset) by default. The return status when listing options is zero if all _o_p_t_n_a_m_e_s are enabled, non-zero otherwise. When setting or unsetting options, the return status is zero unless an _o_p_t_n_a_m_e is not a valid shell option. The list of sshhoopptt options is: aauuttooccdd If set, a command name that is the name of a directory is executed as if it were the argument to the ccdd com- mand. This option is only used by interactive shells. ccddaabbllee__vvaarrss If set, an argument to the ccdd builtin command that is not a directory is assumed to be the name of a variable whose value is the directory to change to. ccddssppeellll If set, minor errors in the spelling of a directory com- ponent in a ccdd command will be corrected. The errors checked for are transposed characters, a missing charac- ter, and one character too many. If a correction is found, the corrected file name is printed, and the com- mand proceeds. This option is only used by interactive shells. cchheecckkhhaasshh If set, bbaasshh checks that a command found in the hash ta- ble exists before trying to execute it. If a hashed command no longer exists, a normal path search is per- formed. cchheecckkjjoobbss If set, bbaasshh lists the status of any stopped and running jobs before exiting an interactive shell. If any jobs are running, this causes the exit to be deferred until a second exit is attempted without an intervening command (see JJOOBB CCOONNTTRROOLL above). The shell always postpones exiting if any jobs are stopped. cchheecckkwwiinnssiizzee If set, bbaasshh checks the window size after each command and, if necessary, updates the values of LLIINNEESS and CCOOLL-- UUMMNNSS. ccmmddhhiisstt If set, bbaasshh attempts to save all lines of a multiple- line command in the same history entry. This allows easy re-editing of multi-line commands. ccoommppaatt3311 If set, bbaasshh changes its behavior to that of version 3.1 with respect to quoted arguments to the conditional com- mand's =~ operator. ccoommppaatt3322 If set, bbaasshh changes its behavior to that of version 3.2 with respect to locale-specific string comparison when using the conditional command's < and > operators. ccoommppaatt4400 If set, bbaasshh changes its behavior to that of version 4.0 with respect to locale-specific string comparison when using the conditional command's < and > operators and the effect of interrupting a command list. ddiirrssppeellll If set, bbaasshh attempts spelling correction on directory names during word completion if the directory name ini- tially supplied does not exist. ddoottgglloobb If set, bbaasshh includes filenames beginning with a `.' in the results of pathname expansion. eexxeeccffaaiill If set, a non-interactive shell will not exit if it can- not execute the file specified as an argument to the eexxeecc builtin command. An interactive shell does not exit if eexxeecc fails. eexxppaanndd__aalliiaasseess If set, aliases are expanded as described above under AALLIIAASSEESS. This option is enabled by default for interac- tive shells. eexxttddeebbuugg If set, behavior intended for use by debuggers is enabled: 11.. The --FF option to the ddeeccllaarree builtin displays the source file name and line number corresponding to each function name supplied as an argument. 22.. If the command run by the DDEEBBUUGG trap returns a non-zero value, the next command is skipped and not executed. 33.. If the command run by the DDEEBBUUGG trap returns a value of 2, and the shell is executing in a sub- routine (a shell function or a shell script exe- cuted by the .. or ssoouurrccee builtins), a call to rreettuurrnn is simulated. 44.. BBAASSHH__AARRGGCC and BBAASSHH__AARRGGVV are updated as described in their descriptions above. 55.. Function tracing is enabled: command substitu- tion, shell functions, and subshells invoked with (( _c_o_m_m_a_n_d )) inherit the DDEEBBUUGG and RREETTUURRNN traps. 66.. Error tracing is enabled: command substitution, shell functions, and subshells invoked with (( _c_o_m_m_a_n_d )) inherit the EERRRROORR trap. eexxttgglloobb If set, the extended pattern matching features described above under PPaatthhnnaammee EExxppaannssiioonn are enabled. eexxttqquuoottee If set, $$'_s_t_r_i_n_g' and $$"_s_t_r_i_n_g" quoting is performed within $${{_p_a_r_a_m_e_t_e_r}} expansions enclosed in double quotes. This option is enabled by default. ffaaiillgglloobb If set, patterns which fail to match filenames during pathname expansion result in an expansion error. ffoorrccee__ffiiggnnoorree If set, the suffixes specified by the FFIIGGNNOORREE shell variable cause words to be ignored when performing word completion even if the ignored words are the only possi- ble completions. See SSHHEELLLL VVAARRIIAABBLLEESS above for a description of FFIIGGNNOORREE. This option is enabled by default. gglloobbssttaarr If set, the pattern **** used in a pathname expansion con- text will match a files and zero or more directories and subdirectories. If the pattern is followed by a //, only directories and subdirectories match. ggnnuu__eerrrrffmmtt If set, shell error messages are written in the standard GNU error message format. hhiissttaappppeenndd If set, the history list is appended to the file named by the value of the HHIISSTTFFIILLEE variable when the shell exits, rather than overwriting the file. hhiissttrreeeeddiitt If set, and rreeaaddlliinnee is being used, a user is given the opportunity to re-edit a failed history substitution. hhiissttvveerriiffyy If set, and rreeaaddlliinnee is being used, the results of his- tory substitution are not immediately passed to the shell parser. Instead, the resulting line is loaded into the rreeaaddlliinnee editing buffer, allowing further modi- fication. hhoossttccoommpplleettee If set, and rreeaaddlliinnee is being used, bbaasshh will attempt to perform hostname completion when a word containing a @@ is being completed (see CCoommpplleettiinngg under RREEAADDLLIINNEE above). This is enabled by default. hhuuppoonneexxiitt If set, bbaasshh will send SSIIGGHHUUPP to all jobs when an inter- active login shell exits. iinntteerraaccttiivvee__ccoommmmeennttss If set, allow a word beginning with ## to cause that word and all remaining characters on that line to be ignored in an interactive shell (see CCOOMMMMEENNTTSS above). This option is enabled by default. lliitthhiisstt If set, and the ccmmddhhiisstt option is enabled, multi-line commands are saved to the history with embedded newlines rather than using semicolon separators where possible. llooggiinn__sshheellll The shell sets this option if it is started as a login shell (see IINNVVOOCCAATTIIOONN above). The value may not be changed. mmaaiillwwaarrnn If set, and a file that bbaasshh is checking for mail has been accessed since the last time it was checked, the message ``The mail in _m_a_i_l_f_i_l_e has been read'' is dis- played. nnoo__eemmppttyy__ccmmdd__ccoommpplleettiioonn If set, and rreeaaddlliinnee is being used, bbaasshh will not attempt to search the PPAATTHH for possible completions when completion is attempted on an empty line. nnooccaasseegglloobb If set, bbaasshh matches filenames in a case-insensitive fashion when performing pathname expansion (see PPaatthhnnaammee EExxppaannssiioonn above). nnooccaasseemmaattcchh If set, bbaasshh matches patterns in a case-insensitive fashion when performing matching while executing ccaassee or [[[[ conditional commands. nnuullllgglloobb If set, bbaasshh allows patterns which match no files (see PPaatthhnnaammee EExxppaannssiioonn above) to expand to a null string, rather than themselves. pprrooggccoommpp If set, the programmable completion facilities (see PPrroo-- ggrraammmmaabbllee CCoommpplleettiioonn above) are enabled. This option is enabled by default. pprroommppttvvaarrss If set, prompt strings undergo parameter expansion, com- mand substitution, arithmetic expansion, and quote removal after being expanded as described in PPRROOMMPPTTIINNGG above. This option is enabled by default. rreessttrriicctteedd__sshheellll The shell sets this option if it is started in restricted mode (see RREESSTTRRIICCTTEEDD SSHHEELLLL below). The value may not be changed. This is not reset when the startup files are executed, allowing the startup files to dis- cover whether or not a shell is restricted. sshhiifftt__vveerrbboossee If set, the sshhiifftt builtin prints an error message when the shift count exceeds the number of positional parame- ters. ssoouurrcceeppaatthh If set, the ssoouurrccee (..) builtin uses the value of PPAATTHH to find the directory containing the file supplied as an argument. This option is enabled by default. xxppgg__eecchhoo If set, the eecchhoo builtin expands backslash-escape sequences by default. ssuussppeenndd [--ff] Suspend the execution of this shell until it receives a SSIIGGCCOONNTT signal. A login shell cannot be suspended; the --ff option can be used to override this and force the suspension. The return sta- tus is 0 unless the shell is a login shell and --ff is not sup- plied, or if job control is not enabled. tteesstt _e_x_p_r [[ _e_x_p_r ]] Return a status of 0 or 1 depending on the evaluation of the conditional expression _e_x_p_r. Each operator and operand must be a separate argument. Expressions are composed of the primaries described above under CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS. tteesstt does not accept any options, nor does it accept and ignore an argument of ---- as signifying the end of options. Expressions may be combined using the following operators, listed in decreasing order of precedence. The evaluation depends on the number of arguments; see below. !! _e_x_p_r True if _e_x_p_r is false. (( _e_x_p_r )) Returns the value of _e_x_p_r. This may be used to override the normal precedence of operators. _e_x_p_r_1 -aa _e_x_p_r_2 True if both _e_x_p_r_1 and _e_x_p_r_2 are true. _e_x_p_r_1 -oo _e_x_p_r_2 True if either _e_x_p_r_1 or _e_x_p_r_2 is true. tteesstt and [[ evaluate conditional expressions using a set of rules based on the number of arguments. 0 arguments The expression is false. 1 argument The expression is true if and only if the argument is not null. 2 arguments If the first argument is !!, the expression is true if and only if the second argument is null. If the first argu- ment is one of the unary conditional operators listed above under CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS, the expression is true if the unary test is true. If the first argument is not a valid unary conditional operator, the expression is false. 3 arguments If the second argument is one of the binary conditional operators listed above under CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS, the result of the expression is the result of the binary test using the first and third arguments as operands. The --aa and --oo operators are considered binary operators when there are three arguments. If the first argument is !!, the value is the negation of the two-argument test using the second and third arguments. If the first argument is exactly (( and the third argument is exactly )), the result is the one-argument test of the second argument. Other- wise, the expression is false. 4 arguments If the first argument is !!, the result is the negation of the three-argument expression composed of the remaining arguments. Otherwise, the expression is parsed and eval- uated according to precedence using the rules listed above. 5 or more arguments The expression is parsed and evaluated according to precedence using the rules listed above. ttiimmeess Print the accumulated user and system times for the shell and for processes run from the shell. The return status is 0. ttrraapp [--llpp] [[_a_r_g] _s_i_g_s_p_e_c ...] The command _a_r_g is to be read and executed when the shell receives signal(s) _s_i_g_s_p_e_c. If _a_r_g is absent (and there is a single _s_i_g_s_p_e_c) or --, each specified signal is reset to its original disposition (the value it had upon entrance to the shell). If _a_r_g is the null string the signal specified by each _s_i_g_s_p_e_c is ignored by the shell and by the commands it invokes. If _a_r_g is not present and --pp has been supplied, then the trap commands associated with each _s_i_g_s_p_e_c are displayed. If no arguments are supplied or if only --pp is given, ttrraapp prints the list of commands associated with each signal. The --ll option causes the shell to print a list of signal names and their cor- responding numbers. Each _s_i_g_s_p_e_c is either a signal name defined in <_s_i_g_n_a_l_._h>, or a signal number. Signal names are case insensitive and the SIG prefix is optional. If a _s_i_g_s_p_e_c is EEXXIITT (0) the command _a_r_g is executed on exit from the shell. If a _s_i_g_s_p_e_c is DDEEBBUUGG, the command _a_r_g is exe- cuted before every _s_i_m_p_l_e _c_o_m_m_a_n_d, _f_o_r command, _c_a_s_e command, _s_e_l_e_c_t command, every arithmetic _f_o_r command, and before the first command executes in a shell function (see SSHHEELLLL GGRRAAMMMMAARR above). Refer to the description of the eexxttddeebbuugg option to the sshhoopptt builtin for details of its effect on the DDEEBBUUGG trap. If a _s_i_g_s_p_e_c is RREETTUURRNN, the command _a_r_g is executed each time a shell function or a script executed with the .. or ssoouurrccee builtins fin- ishes executing. If a _s_i_g_s_p_e_c is EERRRR, the command _a_r_g is executed whenever a sim- ple command has a non-zero exit status, subject to the following conditions. The EERRRR trap is not executed if the failed command is part of the command list immediately following a wwhhiillee or uunnttiill keyword, part of the test in an _i_f statement, part of a command executed in a &&&& or |||| list, or if the command's return value is being inverted via !!. These are the same conditions obeyed by the eerrrreexxiitt option. Signals ignored upon entry to the shell cannot be trapped or reset. Trapped signals that are not being ignored are reset to their original values in a subshell or subshell environment when one is created. The return status is false if any _s_i_g_s_p_e_c is invalid; otherwise ttrraapp returns true. ttyyppee [--aaffttppPP] _n_a_m_e [_n_a_m_e ...] With no options, indicate how each _n_a_m_e would be interpreted if used as a command name. If the --tt option is used, ttyyppee prints a string which is one of _a_l_i_a_s, _k_e_y_w_o_r_d, _f_u_n_c_t_i_o_n, _b_u_i_l_t_i_n, or _f_i_l_e if _n_a_m_e is an alias, shell reserved word, function, builtin, or disk file, respectively. If the _n_a_m_e is not found, then nothing is printed, and an exit status of false is returned. If the --pp option is used, ttyyppee either returns the name of the disk file that would be executed if _n_a_m_e were speci- fied as a command name, or nothing if ``type -t name'' would not return _f_i_l_e. The --PP option forces a PPAATTHH search for each _n_a_m_e, even if ``type -t name'' would not return _f_i_l_e. If a command is hashed, --pp and --PP print the hashed value, not necessarily the file that appears first in PPAATTHH. If the --aa option is used, ttyyppee prints all of the places that contain an executable named _n_a_m_e. This includes aliases and functions, if and only if the --pp option is not also used. The table of hashed commands is not consulted when using --aa. The --ff option suppresses shell func- tion lookup, as with the ccoommmmaanndd builtin. ttyyppee returns true if all of the arguments are found, false if any are not found. uulliimmiitt [--HHSSTTaabbccddeeffiillmmnnppqqrrssttuuvvxx [_l_i_m_i_t]] Provides control over the resources available to the shell and to processes started by it, on systems that allow such control. The --HH and --SS options specify that the hard or soft limit is set for the given resource. A hard limit cannot be increased by a non-root user once it is set; a soft limit may be increased up to the value of the hard limit. If neither --HH nor --SS is speci- fied, both the soft and hard limits are set. The value of _l_i_m_i_t can be a number in the unit specified for the resource or one of the special values hhaarrdd, ssoofftt, or uunnlliimmiitteedd, which stand for the current hard limit, the current soft limit, and no limit, respectively. If _l_i_m_i_t is omitted, the current value of the soft limit of the resource is printed, unless the --HH option is given. When more than one resource is specified, the limit name and unit are printed before the value. Other options are inter- preted as follows: --aa All current limits are reported --bb The maximum socket buffer size --cc The maximum size of core files created --dd The maximum size of a process's data segment --ee The maximum scheduling priority ("nice") --ff The maximum size of files written by the shell and its children --ii The maximum number of pending signals --ll The maximum size that may be locked into memory --mm The maximum resident set size (many systems do not honor this limit) --nn The maximum number of open file descriptors (most systems do not allow this value to be set) --pp The pipe size in 512-byte blocks (this may not be set) --qq The maximum number of bytes in POSIX message queues --rr The maximum real-time scheduling priority --ss The maximum stack size --tt The maximum amount of cpu time in seconds --uu The maximum number of processes available to a single user --vv The maximum amount of virtual memory available to the shell --xx The maximum number of file locks --TT The maximum number of threads If _l_i_m_i_t is given, it is the new value of the specified resource (the --aa option is display only). If no option is given, then --ff is assumed. Values are in 1024-byte increments, except for --tt, which is in seconds, --pp, which is in units of 512-byte blocks, and --TT, --bb, --nn, and --uu, which are unscaled values. The return status is 0 unless an invalid option or argument is supplied, or an error occurs while setting a new limit. uummaasskk [--pp] [--SS] [_m_o_d_e] The user file-creation mask is set to _m_o_d_e. If _m_o_d_e begins with a digit, it is interpreted as an octal number; otherwise it is interpreted as a symbolic mode mask similar to that accepted by _c_h_m_o_d(1). If _m_o_d_e is omitted, the current value of the mask is printed. The --SS option causes the mask to be printed in sym- bolic form; the default output is an octal number. If the --pp option is supplied, and _m_o_d_e is omitted, the output is in a form that may be reused as input. The return status is 0 if the mode was successfully changed or if no _m_o_d_e argument was supplied, and false otherwise. uunnaalliiaass [-aa] [_n_a_m_e ...] Remove each _n_a_m_e from the list of defined aliases. If --aa is supplied, all alias definitions are removed. The return value is true unless a supplied _n_a_m_e is not a defined alias. uunnsseett [-ffvv] [_n_a_m_e ...] For each _n_a_m_e, remove the corresponding variable or function. If no options are supplied, or the --vv option is given, each _n_a_m_e refers to a shell variable. Read-only variables may not be unset. If --ff is specified, each _n_a_m_e refers to a shell func- tion, and the function definition is removed. Each unset vari- able or function is removed from the environment passed to sub- sequent commands. If any of CCOOMMPP__WWOORRDDBBRREEAAKKSS, RRAANNDDOOMM, SSEECCOONNDDSS, LLIINNEENNOO, HHIISSTTCCMMDD, FFUUNNCCNNAAMMEE, GGRROOUUPPSS, or DDIIRRSSTTAACCKK are unset, they lose their special properties, even if they are subsequently reset. The exit status is true unless a _n_a_m_e is readonly. wwaaiitt [_n _._._.] Wait for each specified process and return its termination sta- tus. Each _n may be a process ID or a job specification; if a job spec is given, all processes in that job's pipeline are waited for. If _n is not given, all currently active child pro- cesses are waited for, and the return status is zero. If _n specifies a non-existent process or job, the return status is 127. Otherwise, the return status is the exit status of the last process or job waited for. SSEEEE AALLSSOO bash(1), sh(1) GNU Bash-4.0 2004 Apr 20 BASH_BUILTINS(1)