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bsh(1)									bsh(1)

NAME
     bsh, jsh - shell, the standard/job control command programming language

SYNOPSIS
     bsh [ -acefhiknprstuvx ] [ args ]
     jsh [ -acefhiknprstuvx ] [ args ]

DESCRIPTION
     Note: This is the Bourne shell description. All references to sh and
     shell pertain to bsh and all references below to /usr/lib/rsh, the
     restricted shell, no longer apply to the Bourne shell. (See sh(1)).

     bsh is a command programming language that executes commands read from a
     terminal or a file.

     jsh is an interface to the shell that provides all the functionality of
     sh and enables Job Control (see Job Control below).

     See Invocation below for the meaning of arguments to the shell.

     See CAVEATS below for interaction with Korn shell builtins.

   Definitions
     A blank is a tab or a space.  A name is a sequence of letters, digits, or
     underscores beginning with a letter or underscore.	 A parameter is a
     name, a digit, or any of the characters *, @, #, ?, -, $, and ! .

   Commands
     A simple-command is a sequence of non-blank words separated by blanks.
     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 exec(2)).
     The value of a simple-command is its exit status if it terminates
     normally, or (octal) 200+status if it terminates abnormally (see
     signal(2) for a list of status values).

     A pipeline is a sequence of one or more commands separated by |.  The
     standard output of each command but the last is connected by a pipe(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 list 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
     not wait for that pipeline to finish).  The symbol && (||) causes the
     list 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 list, instead of semicolons, to delimit commands.

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bsh(1)									bsh(1)

     A command is either a simple-command or one of the following.  Unless
     otherwise stated, the value returned by a command is that of the last
     simple-command executed in the command.

     for name [ in word ... ] do list done
	       Each time a for command is executed, name is set to the next
	       word taken from the in word list.  If in word ...  is omitted,
	       the for command executes the do list once for each positional
	       parameter that is set (see Parameter Substitution below).
	       Execution ends when there are no more words in the list.

     case word in [ pattern [ | pattern ] ...) list ;; ] ... esac
	       A case command executes the list associated with the first
	       pattern that matches word.  The form of the patterns is the
	       same as that used for filename generation (see Filename
	       Generation) except that a slash, a leading dot, or a dot
	       immediately following a slash need not be matched explicitly.

     if list then list [ elif list then list ] ... [ else list ] fi
	       The list following if is executed and, if it returns a zero
	       exit status, the list following the first then is executed.
	       Otherwise, the list following elif is executed and, if its
	       value is zero, the list following the next then is executed.
	       Failing that, the else list is executed.	 If no else list or
	       then list is executed, the if command returns a zero exit
	       status.

     while list do list done
	       A while command repeatedly executes the while list and, if the
	       exit status of the last command in the list is zero, executes
	       the do list; otherwise the loop terminates.  If no commands in
	       the do list are executed, the while command returns a zero exit
	       status; until can be used in place of while to negate the loop
	       termination test.

     (list)    Execute list in a subshell.

     {list;}   list is executed in the current (that is, parent) shell.	 The {
	       must be followed by a space.

     name () {list;}
	       Define a function that is referenced by name.  The body of the
	       function is the list of commands between { and }.  The list can
	       appear on the same line as the {.  If it does, the { and list
	       must be separated by a space.  The } cannot be on the same line
	       as list; it must be on a newline.  Execution of functions is
	       described below (see Execution).	 The { and } are unnecessary
	       if the body of the function is a command as defined above,
	       under Commands.

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bsh(1)									bsh(1)

     The following words are only recognized as the first word of a command
     and when not quoted:

	  if then else elif fi case esac for while until do done { }

   Comments
     A word beginning with # causes that word and all the following characters
     up to a newline to be ignored.

   Command Substitution
     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 (\newline), 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 \, `, ", newline,
     and $ are left intact when the command string is read.

   Parameter Substitution
     The character $ is used to introduce substitutable parameters.  There are
     two types of parameters, positional and keyword.  If parameter is a
     digit, it is a positional parameter.  Positional parameters can be
     assigned values by set.  Keyword parameters (also known as variables) can
     be assigned values by writing:

	  name = value [ name = value ] ...

     Pattern-matching is not performed on value.  There cannot be a function
     and a variable with the same name.

     ${parameter}	 The value, if any, of the parameter is substituted.
			 The braces are required only when parameter is
			 followed by a letter, digit, or underscore that is
			 not to be interpreted as part of its name.  If
			 parameter is * or @, all the positional parameters,
			 starting with $1, are substituted (separated by
			 spaces).  Parameter $0 is set from argument zero when
			 the shell is invoked.

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bsh(1)									bsh(1)

     ${parameter:-word}	 If parameter is set and is non-null, substitute its
			 value; otherwise substitute word.

     ${parameter:=word}	 If parameter is not set or is null set it to word;
			 the value of the parameter is substituted.
			 Positional parameters cannot be assigned to in this
			 way.

     ${parameter:?word}	 If parameter is set and is non-null, substitute its
			 value; otherwise, print word and exit from the shell.
			 If word is omitted, the message "parameter null or
			 not set" is printed.

     ${parameter:+word}	 If parameter is set and is non-null, substitute word;
			 otherwise substitute nothing.

     In the above, word is not evaluated unless it is to be used as the
     substituted string, so that, in the following example, pwd is executed
     only if d is not set or is null:

	  echo ${d:-`pwd`}

     If the colon (:) is omitted from the above expressions, the shell only
     checks whether parameter is set or not.

     The following parameters are automatically set by the shell:

     *	  Expands to the positional parameters, beginning with 1.

     @	  Expands to the positional parameters beginning with 1, 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 set 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:

     HOME      The default argument (home directory) for the cd command, set
	       to the user's login directory by login(1) from the password
	       file (see passwd(4)).

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bsh(1)									bsh(1)

     PATH      The search path for commands (see Execution below).  The user
	       cannot change PATH if executing under rsh.

     CDPATH    The search path for the cd command.

     MAIL      If this parameter is set to the name of a mail file and the
	       MAILPATH parameter is not set, the shell informs the user of
	       the arrival of mail in the specified file.

     MAILCHECK This parameter specifies how often (in seconds) the shell
	       checks for the arrival of mail in the files specified by the
	       MAILPATH or MAIL parameters.  The default value is 600 seconds
	       (10 minutes).  If set to 0, the shell checks before each
	       prompt.

     MAILPATH  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".

     PS1       Primary prompt string, by default ``$ ''.

     PS2       Secondary prompt string, by default ``> ''.

     IFS       Internal field separators, normally space, tab, and newline.

     SHACCT    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.

     SHELL     When the shell is invoked, it scans the environment (see
	       Environment 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 PATH, PS1, PS2, MAILCHECK, and IFS.
     HOME and MAIL are set by login(1).

   Blank Interpretation
     After parameter and command substitution, the results of substitution are
     scanned for internal field separator characters (those found in IFS) and
     split into distinct arguments where such characters are found.  Explicit
     null arguments ("" or '') are retained.  Implicit null arguments (those
     resulting from parameters that have no values) are removed.  The original
     whitespace characters (space, tab, and newline) are always considered
     internal field separators.

   Input/Output
     A command's input and output can be redirected using a special notation
     interpreted by the shell.	The following can appear anywhere in a
     simple-command or can precede or follow a command and are not passed on

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bsh(1)									bsh(1)

     as arguments to the invoked command.  Note that parameter and command
     substitution occurs before word or digit is used.

     <word     Use file word as standard input (file descriptor 0).

     >word     Use file word as standard output (file descriptor 1).  If the
	       file does not exist it is created; otherwise, it is truncated
	       to zero length.

     >>word    Use file word 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.

     <<[-]word After parameter and command substitution is done on word, the
	       shell input is read up to the first line that literally matches
	       the resulting word, or to an end-of-file.  If, however, - is
	       appended to <<:

	       1.  Leading tabs are stripped from word before the shell input
		   is read (but after parameter and command substitution is
		   done on word).

	       2.  Leading tabs are stripped from the shell input as it is
		   read and before each line is compared with word.

	       3.  Shell input is read up to the first line that literally
		   matches the resulting word, or to an end-of-file.

	       If any character of word is quoted (see Quoting, later), no
	       additional processing is done to the shell input.  If no
	       characters of word are quoted:

	       1.  Parameter and command substitution occurs.

	       2.  (Escaped) \newline is ignored.

	       3.  \ must be used to quote the characters \, $, and `.

	       The resulting document becomes the standard input.

     <&digit   Use the file associated with file descriptor digit as standard
	       input.  Similarly for the standard output using >&digit.

     <&-       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:

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bsh(1)									bsh(1)

	  ... 2>&1

     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:

	  ... 1>xxx 2>&1

     first associates file descriptor 1 with file xxx.	It associates file
     descriptor 2 with the file associated with file descriptor 1 (that is,
     xxx).  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 xxx.

     Using the terminology introduced on the first page, under Commands, if a
     command is composed of several simple commands, redirection is evaluated
     for the entire command before it is evaluated for each simple command.
     That is, the shell evaluates redirection for the entire list, then each
     pipeline within the list, then each command within each pipeline, then
     each list within each command.

     If a command is followed by & the default standard input for the command
     is the empty file /dev/null.  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.

   Filename Generation
     Before a command is executed, each command word is scanned for the
     characters *, ?, and [.  If one of these characters appears the word is
     regarded as a pattern.  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.

   Quoting
     The following characters have a special meaning to the shell and cause
     termination of a word unless quoted:

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bsh(1)									bsh(1)

	  ;  &	(  )  |	 ^  <  >  newline  space  tab

     A character can be quoted 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 \newline 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 ("$1 $2 ..."); however, if $@ is within a pair of double
     quotes, the positional parameters are substituted and quoted, separated
     by unquoted spaces ("$1" "$2" ...).  \ quotes the characters \, `, ", and
     $.	 The pair \newline 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.

   Prompting
     When used interactively, the shell prompts with the value of PS1 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 PS2) is issued.

   Environment
     The environment (see environ(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 export command is used to bind the
     shell's parameter to the environment (see also set -a).  A parameter can
     be removed from the environment with the unset 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
     unset, plus any modifications or additions, all of which must be noted in
     export commands.

     The environment for any simple-command 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 cmd is concerned if cmd is not a
     Special Command):

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bsh(1)									bsh(1)

	  TERM=450 cmd
	  (export TERM; TERM=450; cmd)

     If cmd is a Special Command, then

	  TERM=45 cmd

     modifies the TERM variable in the current shell.

     If the -k flag is set, all keyword arguments are placed in the
     environment, even if they occur after the command name.  The following
     first prints a=b c and c:

	  echo a=b c
	  set -k
	  echo a=b c

   Signals
     When a command is run in the background (cmd &) under sh, 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 trap, below, or signal(2).)  When a
     command is run in the background under jsh, 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 trap command
     below.

   Execution
     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 Special Commands listed below, it is
     executed in the shell process.  The positional parameters $1, $2, 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
     exec(2).

     The shell parameter PATH defines the search path for the directory
     containing the command.  Alternative directory names are separated by a
     colon (:).	 The default path is:

	  :/usr/sbin:/usr/bsd:/bin:/usr/bin:/usr/bin/X11

     specifying the current directory, /usr/sbin, /usr/bsd, /bin, /usr/bin,
     and /usr/bin/X11, in that order.  Note that the current directory is

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     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 a.out 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 execs 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 PATH variable is changed or the hash -r command is
     executed (see below).

   Special Commands
     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 Job Control).

     :			 No effect; the command does nothing.  A zero exit
			 code is returned.

     . file		 Read and execute commands from file and return.  The
			 search path specified by PATH is used to find the
			 directory containing file.

     break [ n ]	 Exit from the enclosing for or while loop, if any.
			 If n is specified break n levels.

     continue [ n ]	 Resume the next iteration of the enclosing for or
			 while loop.  If n is specified resume at the n-th
			 enclosing loop.

     cd [ arg ]		 Change the current directory to arg.  The shell
			 parameter HOME is the default arg.  The shell
			 parameter CDPATH defines the search path for the
			 directory containing arg.  Alternative directory
			 names are separated by a colon (:).  The default path
			 is <null> (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 arg begins with a / the search
			 path is not used.  Otherwise, each directory in the
			 path is searched for arg.  The cd command cannot be
			 executed by rsh.

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     echo [ arg ... ]	 Echo arguments.  See echo(1) for usage and
			 description.

     eval [ arg ... ]	 The arguments are read as input to the shell and the
			 resulting command(s) executed.

     exec [ arg ... ]	 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.

     exit [ 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.)

     export [ name ... ] The given names are marked for automatic export to
			 the environment 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 not exported.

     getopts		 Use in shell scripts to support command syntax
			 standards (see intro(1)); it parses positional
			 parameters and checks for legal options.  See
			 getopts(1) for usage and description.

     hash [ -r ] [ name ... ]
			 For each name, the location in the search path of the
			 command specified by name is determined and
			 remembered by the shell.  The -r option causes the
			 shell to forget all remembered locations.  If no
			 arguments are given, information about remembered
			 commands is presented.	 hits is the number of times a
			 command has been invoked by the shell process.	 cost
			 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 hits information.  cost is
			 incremented when the recalculation is done.

     limit [ -h ] [ resource [maximum-use ] ]
			 Limits the consumption by the current process and
			 each process it creates to not individually exceed
			 maximum-use on the specified resource.	 If no

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			 maximum-use is given, then the current limit is
			 printed; if no resource is given, then all
			 limitations are given.	 If the -h 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 cputime, the
			 maximum number of cpu-seconds to be used by each
			 process, filesize, the largest single file that can
			 be created, datasize, the maximum growth of the data
			 region via sbrk(2) beyond the end of the program
			 text, stacksize, the maximum size of the
			 automatically-extended stack region, coredumpsize,
			 the size of the largest core dump created, memoryuse,
			 the maximum amount of physical memory a process can
			 have allocated to it at a given time, descriptors,
			 the maximum number of open files, and vmemory, the
			 maximum total virtual size of the process, including
			 text, data, heap, shared memory, mapped files, stack,
			 and so on.

			 The maximum-use can be given as a (floating point or
			 integer) number followed by a scale factor.  For all
			 limits other than cputime the default scale is k or
			 kilobytes (1024 bytes); a scale factor of m or
			 megabytes can also be used.  For cputime the default
			 scaling is seconds, while m for minutes or h for
			 hours, or a time of the form mm:ss giving minutes and
			 seconds can be used.

			 For both resource names and scale factors,
			 unambiguous prefixes of the names suffice.

     newgrp [ arg ... ]	 Equivalent to exec newgrp arg ....  See newgrp(1) for
			 usage and description.

     pwd		 Print the current working directory.  See pwd(1) for
			 usage and description.

     read [ name ... ]	 One line is read from the standard input and, using
			 the internal field separator, IFS (normally space or
			 tab), to delimit word boundaries, the first word is
			 assigned to the first name, the second word to the
			 second name, and so on, with leftover words assigned
			 to the last name.  Lines can be continued using
			 \newline.  Characters other than newline can be
			 quoted by preceding them with a backslash.  These
			 backslashes are removed before words are assigned to
			 names, and no interpretation is done on the character

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			 that follows the backslash.  The return code is 0
			 unless an end-of-file is encountered.

     readonly [ name ... ]
			 The given names are marked readonly and the values of
			 the these names cannot be changed by subsequent
			 assignment.  If no arguments are given, a list of all
			 readonly names is printed.

     return [ 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.

     set [ --aefhkntuvx [ arg ... ] ]

			 -a   Mark variables that are modified or created for
			      export.

			 -e   Exit immediately if a command exits with a
			      nonzero exit status.

			 -f   Disable filename generation.

			 -h   Locate and remember function commands as
			      functions are defined (function commands are
			      normally located when the function is executed).

			 -k   All keyword arguments are placed in the
			      environment for a command, not just those that
			      precede the command name.

			 -n   Read commands but do not execute them.

			 -t   Exit after reading and executing one command.

			 -u   Treat unset variables as an error when
			      substituting.

			 -v   Print shell input lines as they are read.

			 -x   Print commands and their arguments as they are
			      executed.

			 --   Do not change any of the flags; useful in
			      setting $1 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 $1, $2,
			 ....  If no arguments are given the values of all

								       Page 13

bsh(1)									bsh(1)

			 names are printed.

     shift [ n ]	 The positional parameters from $n+1 ...  are renamed
			 $1 ....  If n is not given, it is assumed to be 1.

     test		 Evaluate conditional expressions.  See test(1) for
			 usage and description.

     times		 Print the accumulated user and system times for
			 processes run from the shell.

     trap [ arg ] [ n ] ...
			 The command arg is to be read and executed when the
			 shell receives signal(s) n.  (Note that arg 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 arg is absent all trap(s) n are reset to their
			 original values.  If arg is the null string this
			 signal is ignored by the shell and by the commands it
			 invokes.  If n is 0 the command arg is executed on
			 exit from the shell.  The trap command with no
			 arguments prints a list of commands associated with
			 each signal number.

     type [ name ... ]	 For each name, indicate how it would be interpreted
			 if used as a command name.

     ulimit [ 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 su(1M)) can raise a ulimit.

     umask [ nnn ]	 The user file creation mask is set to nnn (see
			 umask(1)).  If nnn is omitted, the current value of
			 the mask is printed.

     unlimit [ -h ] [ resource ]
			 Removes the limitation on resource.  If no resource
			 is specified, then all resource limitations are
			 removed.  If -h is given, the corresponding hard
			 limits are removed.  Only the superuser can do this.

     unset [ name ... ]	 For each name, remove the corresponding variable or
			 function.  The variables PATH, PS1, PS2, MAILCHECK
			 and IFS cannot be unset.

								       Page 14

bsh(1)									bsh(1)

     wait [ 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.

   Invocation
     If the shell is invoked through exec(2) and the first character of
     argument zero is -, commands are initially read from /etc/profile and
     from $HOME/.profile, if such files exist.	Thereafter, commands are read
     as described below, which is also the case when the shell is invoked as
     /bin/sh.  The flags below are interpreted by the shell on invocation
     only; Note that unless the -c or -s 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:

     -c string
	  If the -c flag is present, commands are read from string.

     -s	  If the -s 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.

     -i	  If the -i flag is present or if the shell input and output are
	  attached to a terminal, this shell is interactive.  In this case
	  TERMINATE is ignored (so that kill 0 does not kill an interactive
	  shell) and INTERRUPT is caught and ignored (so that wait is
	  interruptible).  In all cases, QUIT is ignored by the shell.

     -p	  If the -p flag is present, the shell skips the processing of the
	  system profile (/etc/profile) and the user profile (.profile) when
	  it starts.

     -r	  If the -r flag is present the shell is a restricted shell.

     The remaining flags and arguments are described under the set command
     above.

   Job Control (jsh)
     When the shell is invoked as jsh, Job Control is enabled in addition to
     all of the functionality described previously for sh.  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 job.	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 stty(1)); 3) a
     stopped job is a job that has been placed in a suspended state, usually

								       Page 15

bsh(1)									bsh(1)

     as a result of a SIGTSTP signal (see signal(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 job
     number, 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 current and previous jobs.  The current job is the most
     recent job to be started or restarted.  The previous job is the first
     noncurrent job.

     The acceptable syntax for a Job Identifier is of the form:

	  %jobid

     where jobid can be specified in any of the following formats:

     % or +    For the current job.

     -	       For the previous job.

     ?string   Specify the job for which the command line uniquely contains
	       string.

     n	       For job number n, where n is a job number.

     pref      Where pref is a unique prefix of the command name (for example,
	       if the command ls -l foo were running in the background, it
	       could be referred to as %ls); pref 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:

     bg [%jobid ...]	 Resumes the execution of a stopped job in the
			 background.  If %jobid is omitted the current job is
			 assumed.

     fg [%jobid ...]	 Resumes the execution of a stopped job in the
			 foreground, also moves an executing background job
			 into the foreground.  If %jobid is omitted the
			 current job is assumed.

     jobs [-p|-l] [%jobid ...]

     jobs -x command [arguments]
			 Reports all jobs that are stopped or executing in the
			 background.  If %jobid is omitted, all jobs that are
			 stopped or running in the background are reported.
			 The following options modify/enhance the output of
			 jobs:

								       Page 16

bsh(1)									bsh(1)

			 -l   Report the process group ID and working
			      directory of the jobs.

			 -p   Report only the process group ID of the jobs.

			 -x   Replace any jobid found in command or arguments
			      with the corresponding process group ID, and
			      then execute command passing it arguments.

     kill [-signal] %jobid
			 Builtin version of kill to provide the functionality
			 of the kill command for processes identified with a
			 jobid.

     stop %jobid . . .	 Stops the execution of a background job(s).

     suspend		 Stops the execution of the current shell (but not if
			 it is the login shell).

     wait [%jobid ...]	 wait builtin accepts a job identifier.	 If %jobid is
			 omitted, wait behaves as described above under
			 Special Commands.

   Restricted Shell (/usr/lib/rsh) Only
     /usr/lib/rsh is used to set up login names and execution environments
     whose capabilities are more controlled than those of the standard shell.
     The actions of /usr/lib/rsh are identical to those of sh, except that the
     following are disallowed:

     o	changing directory (see cd(1))
     o	setting the value of $PATH
     o	specifying path or command names containing /
     o	redirecting output (> and >>)

     The restrictions above are enforced after .profile is interpreted.

     A restricted shell can be invoked in one of the following ways:  (1) rsh
     is the filename part of the last entry in the /etc/passwd file (see
     passwd(4)); (2) the environment variable SHELL exists and rsh is the
     filename part of its value; (3) the shell is invoked and rsh is the
     filename part of argument 0; (4) the shell is invoke with the -r option.

     When a command to be executed is found to be a shell procedure,
     /usr/lib/rsh invokes sh 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 .profile (see
     profile(4)) has complete control over user actions by performing
     guaranteed setup actions and leaving the user in an appropriate directory

								       Page 17

bsh(1)									bsh(1)

     (probably not the login directory).

     The system administrator often sets up a directory of commands (that is,
     /usr/rbin) that can be safely invoked by a restricted shell.  IRIX
     provides a restricted editor, red(1).

EXIT STATUS
     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 exit command above).

   jsh Only
     If the shell is invoked as jsh and an attempt is made to exit the shell
     while there are stopped jobs, the shell issues one warning:

	  UX:jsh:WARNING:there are stopped jobs

     This is the only message.	If another exit attempt is made and there are
     still stopped jobs, they are sent a SIGHUP signal from the kernel and the
     shell is exited.

FILES
     /etc/profile
     $HOME/.profile
     /tmp/sh*
     /dev/null

SEE ALSO
     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).

CAVEATS
     Positional parameters have a range of 0 to 9.  Attempting to use the
     positional parameter $10 gives the contents of $1 followed by a 0, which
     is probably not the desired result.

     Words used for filenames in input/output redirection are not interpreted
     for filename generation (see Filename Generation, above).	For example,
     cat file1 >a* creates a file with the name a*.

     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 wait(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

								       Page 18

bsh(1)									bsh(1)

     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.

NOTES
     Sometimes, particularly when using wildcards, the shell will fail to
     execute a command, and complain with the message
	Arg list or environment too large
     This can often be avoided by using multiple commands, the xargs(1)
     command, or by increasing the ncargs kernel parameter with the
     systune(1m) command.

BUGS
     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 exec the original command.  Use
     the hash command to correct this situation.

     Prior to IRIX Release 5.0, the rsh command invoked the restricted shell.
     This restricted shell command is /usr/lib/rsh and it can be executed by
     using the full pathname.  Beginning with IRIX Release 5.0, the rsh
     command is the remote shell.  See rsh_bsd(1C).

								       Page 19

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