IRIX Base Documentation 2001 May

home *** CD-ROM | disk | FTP | other *** search

/ IRIX Base Documentation 2001 May / SGI IRIX Base Documentation 2001 May.iso / usr / share / catman / u_man / cat1 / bsh.z / bsh

Wrap

Text File | 2001-04-17 | 68.9 KB | 1,255 lines

bbbbsssshhhh((((1111)))) bbbbsssshhhh((((1111)))) NNNNAAAAMMMMEEEE _bbbb_ssss_hhhh_,,,, _jjjj_ssss_hhhh - shell, the standard/job control command programming language SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS _bbbb_ssss_hhhh [ ----aaaacccceeeeffffhhhhiiiikkkknnnnpppprrrrssssttttuuuuvvvvxxxx ] [ args ] _jjjj_ssss_hhhh [ ----aaaacccceeeeffffhhhhiiiikkkknnnnpppprrrrssssttttuuuuvvvvxxxx ] [ args ] DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN NNNNooootttteeee:::: This is the Bourne shell description. All references to _s_h and _s_h_e_l_l pertain to _b_s_h and all references below to /_u_s_r/_l_i_b/_r_s_h, the restricted shell, no longer apply to the Bourne shell. (See _ssss_hhhh_((((_1111_))))). _b_s_h is a command programming language that executes commands read from a terminal or a file. _j_s_h is an interface to the shell that provides all the functionality of _s_h and enables Job Control (see JJJJoooobbbb CCCCoooonnnnttttrrrroooollll below). See IIIInnnnvvvvooooccccaaaattttiiiioooonnnn below for the meaning of arguments to the shell. See CCCCAAAAVVVVEEEEAAAATTTTSSSS below for interaction with Korn shell builtins. DDDDeeeeffffiiiinnnniiiittttiiiioooonnnnssss A _b_l_a_n_k is a tab or a space. A _n_a_m_e is a sequence of letters, digits, or underscores beginning with a letter or underscore. A _p_a_r_a_m_e_t_e_r is a name, a digit, or any of the characters ****, @@@@, ####, ????, ----, $$$$, and !!!! .... CCCCoooommmmmmmmaaaannnnddddssss A _s_i_m_p_l_e-_c_o_m_m_a_n_d is a sequence of non-blank _w_o_r_d_s separated by _b_l_a_n_k_s. The first word specifies the name of the command to be executed. Except as specified below, the remaining words are passed as arguments to the invoked command. The command name is passed as argument 0 (see _e_x_e_c(2)). The _v_a_l_u_e of a _s_i_m_p_l_e-_c_o_m_m_a_n_d is its exit status if it terminates normally, or (octal) 200+_s_t_a_t_u_s if it terminates abnormally (see _s_i_g_n_a_l(2) for a list of status values). A _p_i_p_e_l_i_n_e is a sequence of one or more _c_o_m_m_a_n_d_s separated by ||||. The standard output of each command but the last is connected by a _p_i_p_e(2) to the standard input of the next command. Each command is run as a separate process; the shell waits for the last command to terminate. The exit status of a pipeline is the exit status of the last command. A _l_i_s_t is a sequence of one or more pipelines separated by ;;;;, &&&&, &&&&&&&&, or ||||||||, and optionally terminated by ;;;; or &&&&. Of these four symbols, ;;;; and &&&& have equal precedence, which is lower than that of &&&&&&&& and ||||||||. The symbols &&&&&&&& and |||||||| also have equal precedence. A semicolon (;;;;) causes sequential execution of the preceding pipeline; an ampersand (&&&&) causes asynchronous execution of the preceding pipeline (that is, the shell does _n_o_t wait for that pipeline to finish). The symbol &&&&&&&& (||||||||) causes the _l_i_s_t following it to be executed only if the preceding pipeline returns a zero (nonzero) exit status. An arbitrary number of newlines can appear in a _l_i_s_t, instead of semicolons, to delimit commands. PPPPaaaaggggeeee 1111 bbbbsssshhhh((((1111)))) bbbbsssshhhh((((1111)))) A _c_o_m_m_a_n_d is either a _s_i_m_p_l_e-_c_o_m_m_a_n_d or one of the following. Unless otherwise stated, the value returned by a command is that of the last _s_i_m_p_l_e-_c_o_m_m_a_n_d executed in the command. ffffoooorrrr _n_a_m_e [ iiiinnnn _w_o_r_d ... ] ddddoooo _l_i_s_t ddddoooonnnneeee Each time a ffffoooorrrr command is executed, _n_a_m_e is set to the next _w_o_r_d taken from the iiiinnnn _w_o_r_d list. If iiiinnnn _w_o_r_d ... is omitted, the ffffoooorrrr command executes the ddddoooo _l_i_s_t once for each positional parameter that is set (see PPPPaaaarrrraaaammmmeeeetttteeeerrrr SSSSuuuubbbbssssttttiiiittttuuuuttttiiiioooonnnn below). Execution ends when there are no more words in the list. ccccaaaasssseeee _w_o_r_d iiiinnnn [ _p_a_t_t_e_r_n [ | _p_a_t_t_e_r_n ] ...)))) _l_i_s_t ;;;;;;;; ] ... eeeessssaaaacccc A ccccaaaasssseeee command executes the _l_i_s_t associated with the first _p_a_t_t_e_r_n that matches _w_o_r_d. The form of the patterns is the same as that used for filename generation (see FFFFiiiilllleeeennnnaaaammmmeeee GGGGeeeennnneeeerrrraaaattttiiiioooonnnn) except that a slash, a leading dot, or a dot immediately following a slash need not be matched explicitly. iiiiffff _l_i_s_t tttthhhheeeennnn _l_i_s_t [ eeeelllliiiiffff _l_i_s_t tttthhhheeeennnn _l_i_s_t ] ... [ eeeellllsssseeee _l_i_s_t ] ffffiiii The _l_i_s_t following iiiiffff is executed and, if it returns a zero exit status, the _l_i_s_t following the first tttthhhheeeennnn is executed. Otherwise, the _l_i_s_t following eeeelllliiiiffff is executed and, if its value is zero, the _l_i_s_t following the next tttthhhheeeennnn is executed. Failing that, the eeeellllsssseeee _l_i_s_t is executed. If no eeeellllsssseeee _l_i_s_t or tttthhhheeeennnn _l_i_s_t is executed, the iiiiffff command returns a zero exit status. wwwwhhhhiiiilllleeee _l_i_s_t ddddoooo _l_i_s_t ddddoooonnnneeee A wwwwhhhhiiiilllleeee command repeatedly executes the wwwwhhhhiiiilllleeee _l_i_s_t and, if the exit status of the last command in the list is zero, executes the ddddoooo _l_i_s_t; otherwise the loop terminates. If no commands in the ddddoooo _l_i_s_t are executed, the wwwwhhhhiiiilllleeee command returns a zero exit status; uuuunnnnttttiiiillll can be used in place of wwwwhhhhiiiilllleeee to negate the loop termination test. ((((_l_i_s_t)))) Execute _l_i_s_t in a subshell. {{{{_l_i_s_t;;;;}}}} _l_i_s_t is executed in the current (that is, parent) shell. The {{{{ must be followed by a space. _n_a_m_e (((()))) {{{{_l_i_s_t;;;;}}}} Define a function that is referenced by _n_a_m_e. The body of the function is the _l_i_s_t of commands between {{{{ and }}}}. The _l_i_s_t can appear on the same line as the _{{{{. If it does, the {{{{ and _l_i_s_t must be separated by a space. The }}}} cannot be on the same line as _l_i_s_t; it must be on a newline. Execution of functions is described below (see EEEExxxxeeeeccccuuuuttttiiiioooonnnn). The _{{{{ and _}}}} are unnecessary if the body of the function is a _c_o_m_m_a_n_d as defined above, under CCCCoooommmmmmmmaaaannnnddddssss. PPPPaaaaggggeeee 2222 bbbbsssshhhh((((1111)))) bbbbsssshhhh((((1111)))) The following words are only recognized as the first word of a command and when not quoted: iiiiffff tttthhhheeeennnn eeeellllsssseeee eeeelllliiiiffff ffffiiii ccccaaaasssseeee eeeessssaaaacccc ffffoooorrrr wwwwhhhhiiiilllleeee uuuunnnnttttiiiillll ddddoooo ddddoooonnnneeee {{{{ }}}} CCCCoooommmmmmmmeeeennnnttttssss A word beginning with #### causes that word and all the following characters up to a newline to be ignored. CCCCoooommmmmmmmaaaannnndddd SSSSuuuubbbbssssttttiiiittttuuuuttttiiiioooonnnn The shell reads commands from the string between two grave accents (````````) and the standard output from these commands can be used as all or part of a word. Trailing newlines from the standard output are removed. No interpretation is done on the string before the string is read, except to remove backslashes (\\\\) used to escape other characters. Backslashes can be used to escape a grave accent (````) or another backslash (\\\\) and are removed before the command string is read. Escaping grave accents allows nested command substitution. If the command substitution lies within a pair of double quotes ("""" ............ ````............```` ............ """"), a backslash used to escape a double quote (\\\\"""") is removed; otherwise, it is left intact. If a backslash is used to escape a newline character (\\\\nnnneeeewwwwlllliiiinnnneeee), both the backslash and the newline are removed (see the later section on "Quoting"). In addition, backslashes used to escape dollar signs (\\\\$$$$) are removed. Since no interpretation is done on the command string before it is read, inserting a backslash to escape a dollar sign has no effect. Backslashes that precede characters other than \\\\, ````, """", nnnneeeewwwwlllliiiinnnneeee, and $$$$ are left intact when the command string is read. PPPPaaaarrrraaaammmmeeeetttteeeerrrr SSSSuuuubbbbssssttttiiiittttuuuuttttiiiioooonnnn The character $$$$ is used to introduce substitutable _p_a_r_a_m_e_t_e_r_s. There are two types of parameters, positional and keyword. If _p_a_r_a_m_e_t_e_r is a digit, it is a positional parameter. Positional parameters can be assigned values by sssseeeetttt. Keyword parameters (also known as variables) can be assigned values by writing: _n_a_m_e ==== _v_a_l_u_e [ _n_a_m_e ==== _v_a_l_u_e ] ... Pattern-matching is not performed on _v_a_l_u_e. There cannot be a function and a variable with the same _n_a_m_e. $$$${{{{_p_a_r_a_m_e_t_e_r}}}} The value, if any, of the parameter is substituted. The braces are required only when _p_a_r_a_m_e_t_e_r is followed by a letter, digit, or underscore that is not to be interpreted as part of its name. If _p_a_r_a_m_e_t_e_r is **** or @@@@, all the positional parameters, starting with $$$$1111, are substituted (separated by spaces). Parameter $$$$0000 is set from argument zero when the shell is invoked. PPPPaaaaggggeeee 3333 bbbbsssshhhh((((1111)))) bbbbsssshhhh((((1111)))) $$$${{{{_p_a_r_a_m_e_t_e_r::::----_w_o_r_d}}}} If _p_a_r_a_m_e_t_e_r is set and is non-null, substitute its value; otherwise substitute _w_o_r_d. $$$${{{{_p_a_r_a_m_e_t_e_r::::====_w_o_r_d}}}} If _p_a_r_a_m_e_t_e_r is not set or is null set it to _w_o_r_d; the value of the parameter is substituted. Positional parameters cannot be assigned to in this way. $$$${{{{_p_a_r_a_m_e_t_e_r::::????_w_o_r_d}}}} If _p_a_r_a_m_e_t_e_r is set and is non-null, substitute its value; otherwise, print _w_o_r_d and exit from the shell. If _w_o_r_d is omitted, the message "parameter null or not set" is printed. $$$${{{{_p_a_r_a_m_e_t_e_r::::++++_w_o_r_d}}}} If _p_a_r_a_m_e_t_e_r is set and is non-null, substitute _w_o_r_d; otherwise substitute nothing. In the above, _w_o_r_d is not evaluated unless it is to be used as the substituted string, so that, in the following example, ppppwwwwdddd is executed only if dddd is not set or is null: _eeee_cccc_hhhh_oooo _$$$$_{{{{_dddd_::::_----_````_pppp_wwww_dddd_````_}}}} If the colon (::::) is omitted from the above expressions, the shell only checks whether _p_a_r_a_m_e_t_e_r is set or not. The following parameters are automatically set by the shell: **** Expands to the positional parameters, beginning with _1111. @@@@ Expands to the positional parameters beginning with _1111, except when expanded within double quotes, in which case each positional parameter expands as a separate field. #### The number of positional parameters in decimal. ---- Flags supplied to the shell on invocation or by the sssseeeetttt command. ???? The decimal value returned by the last synchronously executed command. $$$$ The process number of this shell. _$$$$ reports the process ID of the parent shell in all shell constructs, including pipelines, and in parenthesized subshells. !!!! The process number of the last background command invoked. The following parameters are used by the shell: HHHHOOOOMMMMEEEE The default argument (home directory) for the _cccc_dddd command, set to the user's login directory by _llll_oooo_gggg_iiii_nnnn(1) from the password file (see _pppp_aaaa_ssss_ssss_wwww_dddd(4)). PPPPaaaaggggeeee 4444 bbbbsssshhhh((((1111)))) bbbbsssshhhh((((1111)))) PPPPAAAATTTTHHHH The search path for commands (see EEEExxxxeeeeccccuuuuttttiiiioooonnnn below). The user cannot change PPPPAAAATTTTHHHH if executing under _r_s_h. CCCCDDDDPPPPAAAATTTTHHHH The search path for the _c_d command. MMMMAAAAIIIILLLL If this parameter is set to the name of a mail file _a_n_d the MMMMAAAAIIIILLLLPPPPAAAATTTTHHHH parameter is not set, the shell informs the user of the arrival of mail in the specified file. MMMMAAAAIIIILLLLCCCCHHHHEEEECCCCKKKK This parameter specifies how often (in seconds) the shell checks for the arrival of mail in the files specified by the MMMMAAAAIIIILLLLPPPPAAAATTTTHHHH or MMMMAAAAIIIILLLL parameters. The default value is 600 seconds (10 minutes). If set to 0, the shell checks before each prompt. MMMMAAAAIIIILLLLPPPPAAAATTTTHHHH A colon (::::) separated list of filenames. If this parameter is set, the shell informs the user of the arrival of mail in any of the specified files. Each filename can be followed by %%%% and a message to be printed when the modification time changes. The default message is "you have mail". PPPPSSSS1111 Primary prompt string, by default ``$$$$ ''. PPPPSSSS2222 Secondary prompt string, by default ``>>>> ''. IIIIFFFFSSSS Internal field separators, normally ssssppppaaaacccceeee, ttttaaaabbbb, and nnnneeeewwwwlllliiiinnnneeee. SSSSHHHHAAAACCCCCCCCTTTT If this parameter is set to the name of a file writable by the user, the shell writes an accounting record in the file for each shell procedure executed. SSSSHHHHEEEELLLLLLLL When the shell is invoked, it scans the environment (see EEEEnnnnvvvviiiirrrroooonnnnmmmmeeeennnntttt below) for this name. If it is found and 'rsh' is the filename part of its value, the shell becomes a restricted shell. The shell gives default values to PPPPAAAATTTTHHHH, PPPPSSSS1111, PPPPSSSS2222, MMMMAAAAIIIILLLLCCCCHHHHEEEECCCCKKKK, and IIIIFFFFSSSS. HHHHOOOOMMMMEEEE and MMMMAAAAIIIILLLL are set by _l_o_g_i_n(1). BBBBllllaaaannnnkkkk IIIInnnntttteeeerrrrpppprrrreeeettttaaaattttiiiioooonnnn After parameter and command substitution, the results of substitution are scanned for internal field separator characters (those found in IIIIFFFFSSSS) and split into distinct arguments where such characters are found. Explicit null arguments ("""""""" or '''''''') are retained. Implicit null arguments (those resulting from _p_a_r_a_m_e_t_e_r_s that have no values) are removed. The original whitespace characters (space, tab, and newline) are always considered internal field separators. IIIInnnnppppuuuutttt////OOOOuuuuttttppppuuuutttt A command's input and output can be redirected using a special notation interpreted by the shell. The following can appear anywhere in a _s_i_m_p_l_e-_c_o_m_m_a_n_d or can precede or follow a _c_o_m_m_a_n_d and are _n_o_t passed on PPPPaaaaggggeeee 5555 bbbbsssshhhh((((1111)))) bbbbsssshhhh((((1111)))) as arguments to the invoked command. Note that parameter and command substitution occurs before _w_o_r_d or _d_i_g_i_t is used. <<<<wwwwoooorrrrdddd Use file _w_o_r_d as standard input (file descriptor 0). >>>>wwwwoooorrrrdddd Use file _w_o_r_d as standard output (file descriptor 1). If the file does not exist it is created; otherwise, it is truncated to zero length. >>>>>>>>wwwwoooorrrrdddd Use file _w_o_r_d as standard output. If the file exists output is appended to it (by first seeking to the end-of-file); otherwise, the file is created. <<<<<<<<[----]wwwwoooorrrrdddd After parameter and command substitution is done on _w_o_r_d, the shell input is read up to the first line that literally matches the resulting _w_o_r_d, or to an end-of-file. If, however, ---- is appended to <<<<<<<<: 1. Leading tabs are stripped from _w_o_r_d before the shell input is read (but after parameter and command substitution is done on _w_o_r_d). 2. Leading tabs are stripped from the shell input as it is read and before each line is compared with _w_o_r_d. 3. Shell input is read up to the first line that literally matches the resulting _w_o_r_d, or to an end-of-file. If any character of _w_o_r_d is quoted (see QQQQuuuuoooottttiiiinnnngggg, later), no additional processing is done to the shell input. If no characters of _w_o_r_d are quoted: 1. Parameter and command substitution occurs. 2. (Escaped) \\\\nnnneeeewwwwlllliiiinnnneeee is ignored. 3. \\\\ must be used to quote the characters \\\\, $$$$, and ````. The resulting document becomes the standard input. <<<<&&&&_d_i_g_i_t Use the file associated with file descriptor _d_i_g_i_t as standard input. Similarly for the standard output using >>>>&&&&_d_i_g_i_t. <<<<&&&&---- The standard input is closed. Similarly for the standard output using >>>>&&&&----. If any of the above is preceded by a digit, the file descriptor that will be associated with the file is that specified by the digit (instead of the default 0 or 1). For example: PPPPaaaaggggeeee 6666 bbbbsssshhhh((((1111)))) bbbbsssshhhh((((1111)))) _...._...._.... _2222_>>>>_&&&&_1111 associates file descriptor 2 with the file currently associated with file descriptor 1. The order in which redirections are specified is significant. The shell evaluates redirections left-to-right. For example: _...._...._.... _1111_>>>>_x_x_x _2222_>>>>_&&&&_1111 first associates file descriptor 1 with file _x_x_x. It associates file descriptor 2 with the file associated with file descriptor 1 (that is, _x_x_x). If the order of redirections were reversed, file descriptor 2 would be associated with the terminal (assuming file descriptor 1 had been) and file descriptor 1 would be associated with file _x_x_x. Using the terminology introduced on the first page, under CCCCoooommmmmmmmaaaannnnddddssss, if a _c_o_m_m_a_n_d is composed of several _s_i_m_p_l_e _c_o_m_m_a_n_d_s, redirection is evaluated for the entire _c_o_m_m_a_n_d before it is evaluated for each _s_i_m_p_l_e _c_o_m_m_a_n_d. That is, the shell evaluates redirection for the entire _l_i_s_t, then each _p_i_p_e_l_i_n_e within the _l_i_s_t, then each _c_o_m_m_a_n_d within each _p_i_p_e_l_i_n_e, then each _l_i_s_t within each _c_o_m_m_a_n_d. If a command is followed by &&&& the default standard input for the command is the empty file /_d_e_v/_n_u_l_l. Otherwise, the environment for the execution of a command contains the file descriptors of the invoking shell as modified by input/output specifications. Redirection of output is not allowed in the restricted shell. FFFFiiiilllleeeennnnaaaammmmeeee GGGGeeeennnneeeerrrraaaattttiiiioooonnnn Before a command is executed, each command _w_o_r_d is scanned for the characters ****, ????, and [[[[. If one of these characters appears the word is regarded as a _p_a_t_t_e_r_n. The word is replaced with alphabetically sorted filenames that match the pattern. If no filename is found that matches the pattern, the word is left unchanged. The character .... at the start of a filename or immediately following a ////, as well as the character //// itself, must be matched explicitly. **** Matches any string, including the null string. ???? Matches any single character. [[[[...]]]] Matches any one of the enclosed characters. A pair of characters separated by ---- matches any character lexically between the pair, inclusive. If the first character following the opening [[[[ is a !!!!, any character not enclosed is matched. QQQQuuuuoooottttiiiinnnngggg The following characters have a special meaning to the shell and cause termination of a word unless quoted: PPPPaaaaggggeeee 7777 bbbbsssshhhh((((1111)))) bbbbsssshhhh((((1111)))) ;;;; &&&& (((( )))) |||| ^^^^ <<<< >>>> nnnneeeewwwwlllliiiinnnneeee ssssppppaaaacccceeee ttttaaaabbbb A character can be _q_u_o_t_e_d that is, made to stand for itself) by preceding it with a backslash (\\\\) or inserting it between a pair of quote marks ('''''''' or """"""""). During processing, the shell can quote certain characters to prevent them from taking on a special meaning. Backslashes used to quote a single character are removed from the word before the command is executed. The pair \\\\nnnneeeewwwwlllliiiinnnneeee is removed from a word before command and parameter substitution. All characters enclosed between a pair of single quote marks (''''''''), except a single quote, are quoted by the shell. Backslash has no special meaning inside a pair of single quotes. A single quote can be quoted inside a pair of double quote marks (for example, """"''''""""). Inside a pair of double quote marks (""""""""), parameter and command substitution occurs and the shell quotes the results to avoid blank interpretation and filename generation. If $$$$**** is within a pair of double quotes, the positional parameters are substituted and quoted, separated by quoted spaces (""""$$$$1111 $$$$2222 ...""""); however, if $$$$@@@@ is within a pair of double quotes, the positional parameters are substituted and quoted, separated by unquoted spaces (""""$$$$1111"""" """"$$$$2222"""" ...). \\\\ quotes the characters \\\\, ````, """", and $$$$. The pair \\\\nnnneeeewwwwlllliiiinnnneeee is removed before parameter and command substitution. If a backslash precedes characters other than \\\\, ````, """", $$$$, and newline, then the backslash itself is quoted by the shell. PPPPrrrroooommmmppppttttiiiinnnngggg When used interactively, the shell prompts with the value of PPPPSSSS1111 before reading a command. If at any time a newline is typed and further input is needed to complete a command, the secondary prompt that is, the value of PPPPSSSS2222) is issued. EEEEnnnnvvvviiiirrrroooonnnnmmmmeeeennnntttt The _e_n_v_i_r_o_n_m_e_n_t (see _e_n_v_i_r_o_n(5)) is a list of name-value pairs that is passed to an executed program in the same way as a normal argument list. The shell interacts with the environment in several ways. On invocation, the shell scans the environment and creates a parameter for each name found, giving it the corresponding value. If the user modifies the value of any of these parameters or creates new parameters, none of these affects the environment unless the eeeexxxxppppoooorrrrtttt command is used to bind the shell's parameter to the environment (see also sssseeeetttt ----aaaa). A parameter can be removed from the environment with the uuuunnnnsssseeeetttt command. The environment seen by any executed command is thus composed of any unmodified name- value pairs originally inherited by the shell, minus any pairs removed by uuuunnnnsssseeeetttt, plus any modifications or additions, all of which must be noted in eeeexxxxppppoooorrrrtttt commands. The environment for any _s_i_m_p_l_e-_c_o_m_m_a_n_d can be augmented by prefixing it with one or more assignments to parameters. Thus these two commands are equivalent (as far as the execution of _c_m_d is concerned if _c_m_d is not a Special Command): PPPPaaaaggggeeee 8888 bbbbsssshhhh((((1111)))) bbbbsssshhhh((((1111)))) _TTTT_EEEE_RRRR_MMMM_====_4444_5555_0000 _cccc_mmmm_dddd _((((_eeee_xxxx_pppp_oooo_rrrr_tttt _TTTT_EEEE_RRRR_MMMM_;;;; _TTTT_EEEE_RRRR_MMMM_====_4444_5555_0000_;;;; _cccc_mmmm_dddd_)))) If _c_m_d is a Special Command, then _TTTT_EEEE_RRRR_MMMM_====_4444_5555 _cccc_mmmm_dddd modifies the _TTTT_EEEE_RRRR_MMMM variable in the current shell. If the ----kkkk flag is set, _a_l_l keyword arguments are placed in the environment, even if they occur after the command name. The following first prints aaaa====bbbb cccc and cccc: _eeee_cccc_hhhh_oooo _aaaa_====_bbbb _cccc _ssss_eeee_tttt _----_kkkk _eeee_cccc_hhhh_oooo _aaaa_====_bbbb _cccc SSSSiiiiggggnnnnaaaallllssss When a command is run in the background (_c_m_d _&&&&) under _ssss_hhhh, it can receive INTERRUPT and QUIT signals but ignores them by default. (A background process can override this default behavior via trap or signal. For details, see the description of _tttt_rrrr_aaaa_pppp, below, or _ssss_iiii_gggg_nnnn_aaaa_llll(2).) When a command is run in the background under _jjjj_ssss_hhhh, however, it does not receive INTERRUPT or QUIT signals. Otherwise signals have the values inherited by the shell from its parent, with the exception of signal 11 (SIGSEGV). See also the _tttt_rrrr_aaaa_pppp command below. EEEExxxxeeeeccccuuuuttttiiiioooonnnn Each time a command is executed, the command substitution, parameter substitution, blank interpretation, input/output redirection, and filename generation listed above are carried out. If the command name matches the name of a defined function, the function is executed in the shell process (note how this differs from the execution of shell procedures). If the command name does not match the name of a defined function, but matches one of the SSSSppppeeeecccciiiiaaaallll CCCCoooommmmmmmmaaaannnnddddssss listed below, it is executed in the shell process. The positional parameters $$$$1111, $$$$2222, and so on are set to the arguments of the function. If the command name matches neither a Special Command nor the name of a defined function, a new process is created and an attempt is made to execute the command via _e_x_e_c(2). The shell parameter PPPPAAAATTTTHHHH defines the search path for the directory containing the command. Alternative directory names are separated by a colon (::::). The default path is: ::::////uuuussssrrrr////ssssbbbbiiiinnnn::::////uuuussssrrrr////bbbbssssdddd::::////bbbbiiiinnnn::::////uuuussssrrrr////bbbbiiiinnnn::::////uuuussssrrrr////bbbbiiiinnnn////XXXX11111111 specifying the current directory, /_u_s_r/_s_b_i_n, /_u_s_r/_b_s_d, /_b_i_n, /_u_s_r/_b_i_n, and /_u_s_r/_b_i_n/_X_1_1, in that order. Note that the current directory is PPPPaaaaggggeeee 9999 bbbbsssshhhh((((1111)))) bbbbsssshhhh((((1111)))) specified by a null pathname. It can appear immediately after the equal sign, between two colon delimiters anywhere in the path list, or at the end of the path list. If the command name contains a //// the search path is not used; such commands are not executed by the restricted shell. Otherwise, each directory in the path is searched for an executable file. If the file has execute permission but is not an aaaa....oooouuuutttt file, it is assumed to be a file containing shell commands. A subshell is spawned to read it. A parenthesized command is also executed in a subshell. The location in the search path where a command was found is remembered by the shell (to help avoid unnecessary _e_x_e_c_s later). If the command was found in a relative directory, its location must be re-determined whenever the current directory changes. The shell forgets all remembered locations whenever the PPPPAAAATTTTHHHH variable is changed or the hhhhaaaasssshhhh ----rrrr command is executed (see below). SSSSppppeeeecccciiiiaaaallll CCCCoooommmmmmmmaaaannnnddddssss Input/output redirection is now permitted for these commands. File descriptor 1 is the default output location. When Job Control is enabled, additional Special Commands are added to the shell's environment (see JJJJoooobbbb CCCCoooonnnnttttrrrroooollll). :::: No effect; the command does nothing. A zero exit code is returned. .... _f_i_l_e Read and execute commands from _f_i_l_e and return. The search path specified by PPPPAAAATTTTHHHH is used to find the directory containing _f_i_l_e. bbbbrrrreeeeaaaakkkk [ _n ] Exit from the enclosing ffffoooorrrr or wwwwhhhhiiiilllleeee loop, if any. If _n is specified break _n levels. ccccoooonnnnttttiiiinnnnuuuueeee [ _n ] Resume the next iteration of the enclosing ffffoooorrrr or wwwwhhhhiiiilllleeee loop. If _n is specified resume at the _n-th enclosing loop. ccccdddd [ _a_r_g ] Change the current directory to _a_r_g. The shell parameter HHHHOOOOMMMMEEEE is the default _a_r_g. The shell parameter CCCCDDDDPPPPAAAATTTTHHHH defines the search path for the directory containing _a_r_g. Alternative directory names are separated by a colon (::::). The default path is <<<<nnnnuuuullllllll>>>> (specifying the current directory). Note that the current directory is specified by a null pathname. It can appear immediately after the equal sign or between the colon delimiters anywhere else in the path list. If _a_r_g begins with a //// the search path is not used. Otherwise, each directory in the path is searched for _a_r_g. The _c_d command cannot be executed by _r_s_h. PPPPaaaaggggeeee 11110000 bbbbsssshhhh((((1111)))) bbbbsssshhhh((((1111)))) eeeecccchhhhoooo [ _a_r_g ... ] Echo arguments. See _e_c_h_o(1) for usage and description. eeeevvvvaaaallll [ _a_r_g ... ] The arguments are read as input to the shell and the resulting command(s) executed. eeeexxxxeeeecccc [ _a_r_g ... ] The command specified by the arguments is executed in place of this shell without creating a new process. Input/output arguments can appear and, if no other arguments are given, cause the shell input/output to be modified. eeeexxxxiiiitttt [ _n ] Causes a shell to exit with the exit status specified by _n. If _n is omitted, the exit status is that of the last command executed (an end-of-file also causes the shell to exit.) eeeexxxxppppoooorrrrtttt [ _n_a_m_e ... ] The given _n_a_m_es are marked for automatic export to the _e_n_v_i_r_o_n_m_e_n_t of subsequently-executed commands. If no arguments are given, variable names that have been marked for export during the current shell's execution are listed. (Variable names exported from a parent shell are listed only if they have been exported again during the current shell's execution.) Function names are _n_o_t exported. ggggeeeettttooooppppttttssss Use in shell scripts to support command syntax standards (see _i_n_t_r_o(1)); it parses positional parameters and checks for legal options. See _g_e_t_o_p_t_s(1) for usage and description. hhhhaaaasssshhhh [ ----rrrr ] [ _n_a_m_e ... ] For each _n_a_m_e, the location in the search path of the command specified by _n_a_m_e is determined and remembered by the shell. The ----rrrr option causes the shell to forget all remembered locations. If no arguments are given, information about remembered commands is presented. _h_i_t_s is the number of times a command has been invoked by the shell process. _c_o_s_t is a measure of the work required to locate a command in the search path. If a command is found in a "relative" directory in the search path, after changing to that directory, the stored location of that command is recalculated. Commands for which this is done are indicated by an asterisk (****) adjacent to the _h_i_t_s information. _c_o_s_t is incremented when the recalculation is done. lllliiiimmmmiiiitttt [ ----hhhh ] [ _r_e_s_o_u_r_c_e [_m_a_x_i_m_u_m-_u_s_e ] ] Limits the consumption by the current process and each process it creates to not individually exceed _m_a_x_i_m_u_m-_u_s_e on the specified _r_e_s_o_u_r_c_e. If no PPPPaaaaggggeeee 11111111 bbbbsssshhhh((((1111)))) bbbbsssshhhh((((1111)))) _m_a_x_i_m_u_m-_u_s_e is given, then the current limit is printed; if no _r_e_s_o_u_r_c_e is given, then all limitations are given. If the ----hhhh flag is given, the hard limits are used instead of the current limits. The hard limits impose a ceiling on the values of the current limits. Only the superuser can raise the hard limits, but a user can lower or raise the current limits within the legal range. Resources controllable currently include _c_p_u_t_i_m_e, the maximum number of cpu-seconds to be used by each process, _f_i_l_e_s_i_z_e, the largest single file that can be created, _d_a_t_a_s_i_z_e, the maximum growth of the data region via _s_b_r_k(2) beyond the end of the program text, _s_t_a_c_k_s_i_z_e, the maximum size of the automatically-extended stack region, _c_o_r_e_d_u_m_p_s_i_z_e, the size of the largest core dump created, _m_e_m_o_r_y_u_s_e, the maximum amount of physical memory a process can have allocated to it at a given time, _d_e_s_c_r_i_p_t_o_r_s, the maximum number of open files, and _v_m_e_m_o_r_y, the maximum total virtual size of the process, including text, data, heap, shared memory, mapped files, stack, and so on. The _m_a_x_i_m_u_m-_u_s_e can be given as a (floating point or integer) number followed by a scale factor. For all limits other than _c_p_u_t_i_m_e the default scale is kkkk or kkkkiiiilllloooobbbbyyyytttteeeessss (1024 bytes); a scale factor of mmmm or mmmmeeeeggggaaaabbbbyyyytttteeeessss can also be used. For _c_p_u_t_i_m_e the default scaling is sssseeeeccccoooonnnnddddssss, while mmmm for minutes or hhhh for hours, or a time of the form _m_m::::_s_s giving minutes and seconds can be used. For both _r_e_s_o_u_r_c_e names and scale factors, unambiguous prefixes of the names suffice. nnnneeeewwwwggggrrrrpppp [ _a_r_g ... ] Equivalent to eeeexxxxeeeecccc nnnneeeewwwwggggrrrrpppp _a_r_g .... See _n_e_w_g_r_p(1) for usage and description. ppppwwwwdddd Print the current working directory. See _p_w_d(1) for usage and description. rrrreeeeaaaadddd [ _n_a_m_e ... ] One line is read from the standard input and, using the internal field separator, IIIIFFFFSSSS (normally space or tab), to delimit word boundaries, 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 assigned to the last _n_a_m_e. Lines can be continued using \\\\nnnneeeewwwwlllliiiinnnneeee. Characters other than nnnneeeewwwwlllliiiinnnneeee can be quoted by preceding them with a backslash. These backslashes are removed before words are assigned to _n_a_m_e_s, and no interpretation is done on the character PPPPaaaaggggeeee 11112222 bbbbsssshhhh((((1111)))) bbbbsssshhhh((((1111)))) that follows the backslash. The return code is 0 unless an end-of-file is encountered. rrrreeeeaaaaddddoooonnnnllllyyyy [ _n_a_m_e ... ] The given _n_a_m_es are marked rrrreeeeaaaaddddoooonnnnllllyyyy and the values of the these _n_a_m_es cannot be changed by subsequent assignment. If no arguments are given, a list of all rrrreeeeaaaaddddoooonnnnllllyyyy names is printed. rrrreeeettttuuuurrrrnnnn [ _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. sssseeeetttt [ --------aaaaeeeeffffhhhhkkkknnnnttttuuuuvvvvxxxx [ _a_r_g ... ] ] ----aaaa Mark variables that are modified or created for export. ----eeee Exit immediately if a command exits with a nonzero exit status. ----ffff Disable filename generation. ----hhhh Locate and remember function commands as functions are defined (function commands are normally located when the function is executed). ----kkkk All keyword arguments are placed in the environment for a command, not just those that precede the command name. ----nnnn Read commands but do not execute them. ----tttt Exit after reading and executing one command. ----uuuu Treat unset variables as an error when substituting. ----vvvv Print shell input lines as they are read. ----xxxx Print commands and their arguments as they are executed. -------- Do not change any of the flags; useful in setting $$$$1111 to ----. Using ++++ rather than ---- causes these flags to be turned off. These flags can also be used upon invocation of the shell. The current set of flags can be found in $$$$----. The remaining arguments are positional parameters and are assigned, in order, to $$$$1111, $$$$2222, .... If no arguments are given the values of all PPPPaaaaggggeeee 11113333 bbbbsssshhhh((((1111)))) bbbbsssshhhh((((1111)))) names are printed. sssshhhhiiiifffftttt [ _n ] The positional parameters from $$$$nnnn++++1111 ... are renamed $$$$1111 .... If _n is not given, it is assumed to be 1. tttteeeesssstttt Evaluate conditional expressions. See _t_e_s_t(1) for usage and description. ttttiiiimmmmeeeessss Print the accumulated user and system times for processes run from the shell. ttttrrrraaaapppp [ _a_r_g ] [ _n ] ... The command _a_r_g is to be read and executed when the shell receives signal(s) _n. (Note that _a_r_g is scanned once when the trap is set and once when the trap is taken.) Trap commands are executed in order of signal number. Any attempt to set a trap on a signal that was ignored on entry to the current shell is ineffective. An error results when an attempt is made to trap signal 11 (SIGSEGV--segmentation fault). If _a_r_g is absent all trap(s) _n are reset to their original values. If _a_r_g is the null string this signal is ignored by the shell and by the commands it invokes. If _n is 0 the command _a_r_g is executed on exit from the shell. The ttttrrrraaaapppp command with no arguments prints a list of commands associated with each signal number. ttttyyyyppppeeee [ _n_a_m_e ... ] For each _n_a_m_e, indicate how it would be interpreted if used as a command name. uuuulllliiiimmmmiiiitttt [ _n ] Impose a size limit of _n blocks on files written by the shell and its child processes (files of any size can be read). If _n is omitted, the current limit is printed. You can lower your own ulimit, but only a superuser (see _s_u(1M)) can raise a ulimit. uuuummmmaaaasssskkkk [ _n_n_n ] The user file creation mask is set to _n_n_n (see _u_m_a_s_k(1)). If _n_n_n is omitted, the current value of the mask is printed. uuuunnnnlllliiiimmmmiiiitttt [ ----hhhh ] [ _r_e_s_o_u_r_c_e ] Removes the limitation on _r_e_s_o_u_r_c_e. If no _r_e_s_o_u_r_c_e is specified, then all _r_e_s_o_u_r_c_e limitations are removed. If ----hhhh is given, the corresponding hard limits are removed. Only the superuser can do this. uuuunnnnsssseeeetttt [ _n_a_m_e ... ] For each _n_a_m_e, remove the corresponding variable or function. The variables PPPPAAAATTTTHHHH, PPPPSSSS1111, PPPPSSSS2222, MMMMAAAAIIIILLLLCCCCHHHHEEEECCCCKKKK and IIIIFFFFSSSS cannot be unset. PPPPaaaaggggeeee 11114444 bbbbsssshhhh((((1111)))) bbbbsssshhhh((((1111)))) wwwwaaaaiiiitttt [ _n ] Wait for your background process whose process id is _n and report its termination status. If _n is omitted, all your shell's currently active background processes are waited for and the return code is zero. IIIInnnnvvvvooooccccaaaattttiiiioooonnnn If the shell is invoked through _e_x_e_c(2) and the first character of argument zero is ----, commands are initially read from /_e_t_c/_p_r_o_f_i_l_e and from $_H_O_M_E/._p_r_o_f_i_l_e, if such files exist. Thereafter, commands are read as described below, which is also the case when the shell is invoked as /_b_i_n/_s_h. The flags below are interpreted by the shell on invocation only; Note that unless the ----cccc or ----ssss flag is specified, the first argument is assumed to be the name of a file containing commands, and the remaining arguments are passed as positional parameters to that command file: ----cccc _s_t_r_i_n_g If the ----cccc flag is present, commands are read from _s_t_r_i_n_g. ----ssss If the ----ssss flag is present or if no arguments remain, commands are read from the standard input. Any remaining arguments specify the positional parameters. Shell output (except for Special Commands) is written to file descriptor 2. ----iiii If the ----iiii flag is present or if the shell input and output are attached to a terminal, this shell is _i_n_t_e_r_a_c_t_i_v_e. In this case TERMINATE is ignored (so that kkkkiiiillllllll 0000 does not kill an interactive shell) and INTERRUPT is caught and ignored (so that wwwwaaaaiiiitttt is interruptible). In all cases, QUIT is ignored by the shell. ----pppp If the ----pppp flag is present, the shell skips the processing of the system profile (_////_eeee_tttt_cccc_////_pppp_rrrr_oooo_ffff_iiii_llll_eeee) and the user profile (_...._pppp_rrrr_oooo_ffff_iiii_llll_eeee) when it starts. ----rrrr If the ----rrrr flag is present the shell is a restricted shell. The remaining flags and arguments are described under the _ssss_eeee_tttt command above. JJJJoooobbbb CCCCoooonnnnttttrrrroooollll ((((jjjjsssshhhh)))) When the shell is invoked as _jjjj_ssss_hhhh, Job Control is enabled in addition to all of the functionality described previously for _ssss_hhhh. Typically Job Control is enabled for the interactive shell only. Noninteractive shells typically do not benefit from the added functionality of Job Control. With Job Control enabled every command or pipeline the user enters at the terminal is called a _j_o_b. All jobs exist in one of the following states: foreground, background, or stopped. These terms are defined as follows: 1) a job in the foreground has read and write access to the controlling terminal; 2) a job in the background is denied read access and has conditional write access to the controlling terminal (see _ssss_tttt_tttt_yyyy(1)); 3) a stopped job is a job that has been placed in a suspended state, usually PPPPaaaaggggeeee 11115555 bbbbsssshhhh((((1111)))) bbbbsssshhhh((((1111)))) as a result of a _SSSS_IIII_GGGG_TTTT_SSSS_TTTT_PPPP signal (see _ssss_iiii_gggg_nnnn_aaaa_llll(2)). Jobs in the foreground can be stopped by INTERRUPT or QUIT signals from the keyboard; background jobs cannot be stopped by these signals. Every job the shell starts is assigned a positive integer, called a _j_o_b _n_u_m_b_e_r, which is tracked by the shell and is used, later, as an identifier to indicate a specific job. Additionally the shell keeps track of the _c_u_r_r_e_n_t and _p_r_e_v_i_o_u_s jobs. The _c_u_r_r_e_n_t _j_o_b is the most recent job to be started or restarted. The _p_r_e_v_i_o_u_s _j_o_b is the first noncurrent job. The acceptable syntax for a Job Identifier is of the form: _%%%%_j_o_b_i_d where _j_o_b_i_d can be specified in any of the following formats: _%%%% or _++++ For the current job. _---- For the previous job. _????_s_t_r_i_n_g Specify the job for which the command line uniquely contains _s_t_r_i_n_g. _n For job number _n, where _n is a job number. _p_r_e_f Where _p_r_e_f is a unique prefix of the command name (for example, if the command _llll_ssss _----_llll _ffff_oooo_oooo were running in the background, it could be referred to as _%%%%_llll_ssss); _p_r_e_f cannot contain blanks unless it is quoted. When Job Control is enabled, the following commands are added to the user's environment to manipulate jobs: _bbbb_gggg [_%%%%_j_o_b_i_d ...] Resumes the execution of a stopped job in the background. If _%%%%_j_o_b_i_d is omitted the current job is assumed. _ffff_gggg [_%%%%_j_o_b_i_d ...] Resumes the execution of a stopped job in the foreground, also moves an executing background job into the foreground. If _%%%%_j_o_b_i_d is omitted the current job is assumed. _jjjj_oooo_bbbb_ssss [_----_pppp_||||_----_llll] [_%%%%_j_o_b_i_d ...] _jjjj_oooo_bbbb_ssss _----_xxxx _c_o_m_m_a_n_d [_a_r_g_u_m_e_n_t_s] Reports all jobs that are stopped or executing in the background. If _%%%%_j_o_b_i_d is omitted, all jobs that are stopped or running in the background are reported. The following options modify/enhance the output of _jjjj_oooo_bbbb_ssss: PPPPaaaaggggeeee 11116666 bbbbsssshhhh((((1111)))) bbbbsssshhhh((((1111)))) _----_llll Report the process group ID and working directory of the jobs. _----_pppp Report only the process group ID of the jobs. _----_xxxx Replace any _j_o_b_i_d found in _c_o_m_m_a_n_d or _a_r_g_u_m_e_n_t_s with the corresponding process group ID, and then execute _c_o_m_m_a_n_d passing it _a_r_g_u_m_e_n_t_s. _kkkk_iiii_llll_llll [-_ssss_iiii_gggg_nnnn_aaaa_llll] _%%%%_j_o_b_i_d Builtin version of _kkkk_iiii_llll_llll to provide the functionality of the _kkkk_iiii_llll_llll command for processes identified with a _j_o_b_i_d. _ssss_tttt_oooo_pppp _%%%%_j_o_b_i_d . . . Stops the execution of a background job(s). _ssss_uuuu_ssss_pppp_eeee_nnnn_dddd Stops the execution of the current shell (but not if it is the login shell). _wwww_aaaa_iiii_tttt [_%%%%_j_o_b_i_d ...] _wwww_aaaa_iiii_tttt builtin accepts a job identifier. If _%%%%_j_o_b_i_d is omitted, _wwww_aaaa_iiii_tttt behaves as described above under SSSSppppeeeecccciiiiaaaallll CCCCoooommmmmmmmaaaannnnddddssss. RRRReeeessssttttrrrriiiicccctttteeeedddd SSSShhhheeeellllllll ((((////uuuussssrrrr////lllliiiibbbb////rrrrsssshhhh)))) OOOOnnnnllllyyyy _////_uuuu_ssss_rrrr_////_llll_iiii_bbbb_////_rrrr_ssss_hhhh is used to set up login names and execution environments whose capabilities are more controlled than those of the standard shell. The actions of _////_uuuu_ssss_rrrr_////_llll_iiii_bbbb_////_rrrr_ssss_hhhh are identical to those of _ssss_hhhh, except that the following are disallowed: +o changing directory (see _c_d(1)) +o setting the value of $$$$PPPPAAAATTTTHHHH +o specifying path or command names containing //// +o redirecting output (>>>> and >>>>>>>>) The restrictions above are enforced after ._p_r_o_f_i_l_e is interpreted. A restricted shell can be invoked in one of the following ways: (1) _r_s_h is the filename part of the last entry in the /_e_t_c/_p_a_s_s_w_d file (see _p_a_s_s_w_d(4)); (2) the environment variable SSSSHHHHEEEELLLLLLLL exists and _r_s_h is the filename part of its value; (3) the shell is invoked and _r_s_h is the filename part of argument 0; (4) the shell is invoke with the ----rrrr option. When a command to be executed is found to be a shell procedure, /_u_s_r/_l_i_b/_r_s_h invokes _s_h to execute it. Thus, it is possible to provide to the end-user shell procedures that have access to the full power of the standard shell, while imposing a limited menu of commands; this scheme assumes that the end-user does not have write and execute permissions in the same directory. The net effect of these rules is that the writer of the ._p_r_o_f_i_l_e (see _p_r_o_f_i_l_e(4)) has complete control over user actions by performing guaranteed setup actions and leaving the user in an appropriate directory PPPPaaaaggggeeee 11117777 bbbbsssshhhh((((1111)))) bbbbsssshhhh((((1111)))) (probably _n_o_t the login directory). The system administrator often sets up a directory of commands (that is, /_u_s_r/_r_b_i_n) that can be safely invoked by a restricted shell. IRIX provides a restricted editor, _r_e_d(1). EEEEXXXXIIIITTTT SSSSTTTTAAAATTTTUUUUSSSS Errors detected by the shell, such as syntax errors, cause the shell to return a nonzero exit status. If the shell is being used noninteractively execution of the shell file is abandoned. Otherwise, the shell returns the exit status of the last command executed (see also the eeeexxxxiiiitttt command above). jjjjsssshhhh OOOOnnnnllllyyyy If the shell is invoked as _jjjj_ssss_hhhh and an attempt is made to exit the shell while there are stopped jobs, the shell issues one warning: _UUUU_XXXX_::::_jjjj_ssss_hhhh_::::_WWWW_AAAA_RRRR_NNNN_IIII_NNNN_GGGG_::::_tttt_hhhh_eeee_rrrr_eeee _aaaa_rrrr_eeee _ssss_tttt_oooo_pppp_pppp_eeee_dddd _jjjj_oooo_bbbb_ssss This is the only message. If another exit attempt is made and there are still stopped jobs, they are sent a _SSSS_IIII_GGGG_HHHH_UUUU_PPPP signal from the kernel and the shell is exited. FFFFIIIILLLLEEEESSSS /etc/profile $HOME/....profile /tmp/sh* /dev/null SSSSEEEEEEEE AAAALLLLSSSSOOOO cd(1), echo(1), env(1), getopts(1), intro(1), login(1), newgrp(1), pwd(1), systune(1m), test(1), umask(1), wait(1), xargs(1), dup(2), exec(2), fork(2), getrlimit(2), pipe(2), signal(2), ulimit(2), profile(4). CCCCAAAAVVVVEEEEAAAATTTTSSSS Positional parameters have a range of 0 to 9. Attempting to use the positional parameter $$$$11110000 gives the contents of $$$$1111 followed by a 0000, which is probably not the desired result. Words used for filenames in input/output redirection are not interpreted for filename generation (see FFFFiiiilllleeeennnnaaaammmmeeee GGGGeeeennnneeeerrrraaaattttiiiioooonnnn, above). For example, ccccaaaatttt ffffiiiilllleeee1111 >>>>aaaa**** creates a file with the name aaaa****. Because commands in pipelines are run as separate processes, variables set in a pipeline have no effect on the parent shell. If you get the error message "cannot fork, too many processes", try using the _w_a_i_t(1) command to clean up your background processes. If this doesn't help, the system process table is probably full or you have too many active foreground processes. (There is a limit to the number of process ids associated with your login, and to the number the system can PPPPaaaaggggeeee 11118888 bbbbsssshhhh((((1111)))) bbbbsssshhhh((((1111)))) keep track of.) For compatibility with the POSIX builtin executables linked to /sbin/builtin_exec, the Korn shell parameter expansion ${parameter##pattern} has been implemented only for the specific pattern '*/' to emulate basename. This allows the Bourne shell builtins to work correctly when called with fullpaths e.g. /sbin/jobs. NNNNOOOOTTTTEEEESSSS Sometimes, particularly when using wildcards, the shell will fail to execute a command, and complain with the message AAAArrrrgggg lllliiiisssstttt oooorrrr eeeennnnvvvviiiirrrroooonnnnmmmmeeeennnntttt ttttoooooooo llllaaaarrrrggggeeee This can often be avoided by using multiple commands, the _x_a_r_g_s(1) command, or by increasing the nnnnccccaaaarrrrggggssss kernel parameter with the _s_y_s_t_u_n_e(1m) command. BBBBUUUUGGGGSSSS Only the last process in a pipeline can be waited for. If a command is executed, and a command with the same name is installed in a directory in the search path before the directory where the original command was found, the shell continues to _e_x_e_c the original command. Use the hhhhaaaasssshhhh command to correct this situation. Prior to IRIX Release 5.0, the _rrrr_ssss_hhhh command invoked the restricted shell. This restricted shell command is _////_uuuu_ssss_rrrr_////_llll_iiii_bbbb_////_rrrr_ssss_hhhh and it can be executed by using the full pathname. Beginning with IRIX Release 5.0, the _rrrr_ssss_hhhh command is the remote shell. See _rrrr_ssss_hhhh______bbbb_ssss_dddd(1C). PPPPaaaaggggeeee 11119999