set(1)                                                           set(1)

  set

  NAME

    set - shell built-in to set and clear shell options

  SYNOPSIS

  C shell

    set [-r]

  Korn shell

    set [+-abCefhkmnpsuvxX] [+-o [option]]
        [+-A name] [--] [arg ...]

  DESCRIPTION

  C shell

    The set(1) command displays the value of all shell variables. You can also
    use set(1) to assign the value of a variable to a null string, a word, or
    multiple words (a word list).

    You can repeat these arguments in a single set(1) command to set multiple
    variables, make multiple variables read only, or do both. Note, however,
    that variable expansion happens for all arguments before any setting
    occurs. Note also that "=" can be adjacent to both the variable name and
    the word, or separated from both by white space. It cannot, however, be
    adjacent to only one or the other. See also the unset(1) built-in command.

    -r
        Sets a variable to read only.

  Korn shell

    The set(1) command can be used to set (-) or clear (+) shell options, set
    the positional parameters, or set an array parameter. Options can be
    changed using the +-o option syntax, where option is the long name of an
    option, or using the +-letter syntax, where letter is the option's single
    letter name (not all options have a single letter name).

    The following list provides option letters (if they exist) and long names,
    along with a description of what the option does.
    -A name arg ...
        Sets the elements of the array parameter name to arg.... If -A is
        used, the array is reset (that is, emptied) first; if +A is used, the
        first N elements are set (where N is the number of args), the
        remainder are left untouched.

    -a (allexport)
        All new parameters are created with the export attribute.

    -b (notify)
        Print job notification messages asynchronously, instead of just before
        the prompt. Only used if job control is enabled (-m).

    -C (noclobber)
        Prevent > redirection from overwriting existing files (>| must be used
        to force an overwrite).

    -e (errexit)
        Exit (after executing the ERR trap) as soon as an error occurs or a
        command fails (that is, it exits with a non-zero status). This does
        not apply to commands whose exit status is explicitly tested by a
        shell construct, such as if(1), until(1), while(1), &&, or ||
        statements.

    -f (noglob)
        Do not expand file-name patterns.

    -h (trackall)
        Create tracked aliases for all executed commands. On by default for
        non-interactive shells.

    -i (interactive)
        Enable interactive mode; this can only be set/unset when the shell is
        invoked.

    -k (keyword)
        Parameter assignments are recognized anywhere in a command.

    -l (login)
        The shell is a login shell. This can only be set/unset when the shell
        is invoked.

    -m (monitor)
        Enable job control (default for interactive shells).

    -n (noexec)
        Do not execute any commands. Useful for checking the syntax of scripts
        (ignored if interactive).

    -p (privileged)
        Set automatically if, when the shell starts, the read user identifier
        (UID) or group identifier (GID) does not match the effective UID or
        GID, respectively.

    -r (restricted)
        Enable restricted mode. This option can only be used when the shell is
        invoked.

    -s (stdin)
        If used when the shell is invoked, commands are read from standard
        input. Set automatically if the shell is invoked with no arguments.
        When -s is used in the set(1) command, it causes the specified
        arguments to be sorted before assigning them to the positional
        parameters (or to array name if -A is used).

    -u (nounset)
        Referencing of an unset parameter is treated as an error, unless one
        of the -, +, or = modifiers is used.

    -v (verbose)
        Write shell input to standard error as it is read.

    -x (xtrace)
        Print commands and parameter assignments when they are executed,
        preceded by the value of PS4.

    -X (markdirs)
        Mark directories with a trailing / during file-name generation.

    bgnice
        Background jobs are run with lower priority.

    braceexpand
        Enable brace expansion (also known as alternation).

    cmd_intitle
        Displays the current command line in the terminal window's title bar.

    emacs
        Enable BRL emacs-like command-line editing (interactive shells only).

    gmacs
        Enable gmacs-like (Gosling emacs) command-line editing (interactive
        shells only); currently identical to emacs editing except that
        transpose (^T) acts slightly differently.

    ignoreeof
        The shell will not exit when end-of-file is read, exit(1) must be
        used.

    nohup
        Do not kill running jobs with a HUP signal when a login shell exists.
        Currently set by default, but this will change in the future to be
        compatible with the original Korn shell (which does not have this
        option, but does send the HUP signal).

    nolog
        No effect in the original Korn shell; this prevents function
        definitions from being stored in the history file.

    physical
        Causes the cd(1) and pwd(1) commands to use 'physical' (that is, the
        file system's) .. directories instead of 'logical' directories (the
        shell handles .., which allows the user to remain unaware of symlink
        links to directories). Clear by default. Note that setting this option
        does not affect the current value of the PWD parameter; only the cd(1)
        command changes PWD. See the cd(1) and pwd(1) commands for more
        details.

    posix
        Enable posix mode.

    vi
        Enable vi-like command-line editing (interactive shells only).

    viraw
        No effect. In most implementations of the Korn shell, unless the viraw
        option was set, the vi command-line mode would let the tty driver do
        the work until ESC (^[) was entered. The Interix ksh(1) utility is
        always in viraw mode.

    vi-esccomplete
        In vi command-line editing, perform command completion and file-name
        completion when escape (^[) is entered in command mode.

    vi-show8
        Prefix characters with the eighth-bit set with M-. If this option is
        not set, characters in the range 128-160 are printed as is, which can
        cause problems.

    vi-tabcomplete
        In vi command-line editing, do command completion and file-name
        completion when tab (^I) is entered in insert mode.

    These options can also be used upon invocation of the shell. The current
    set of options (with single-letter names) can be found in the parameter -
    . Using set -o with no option name will list all the options and whether
    each is on or off; set +o will print the long names of all options that
    are currently on.

    Remaining arguments, if any, are positional parameters and are assigned,
    in order, to the positional parameters (that is, 1, 2, and so on). If
    options end with --, and there are no remaining arguments, all positional
    parameters are cleared. If no options or arguments are given, the values
    of all names are printed. For unknown historical reasons, a lone - option
    is treated specially: it clears both the -x and -v options.

  DIAGNOSTICS

  Korn shell

    The set(1) utility exits with status 0 for success, and >0 if an error
    occurred.

  EXAMPLES

  C shell

    set fname = Carl
        Sets fname to Carl.

    set buddy = "Rosana Campana"
        Sets buddy to a string with a space.

    set friends = (Tuttle Chen Solano)
        Sets friends to word list.

    set x=12 y=34 z=56
        Sets x to 12, y to 34, and z to 56.

  Korn shell

    FNAME=Carl
        Sets FNAME to Carl.

    BUDDY="Rosana Campana"
        Sets BUDDY to a string with a space.

    set -x
        Starts command tracing.

    set +x
        Stops command tracing. This is the default setting.

    set -o noclobber
        Prevents file overwriting.

    set +o noclobber
        Allows file overwriting. This is the default setting.