쉘내부명령어의 자세한 도움말을 확인하는 help 활용

[root@su250 ~]# man help

BASH_BUILTINS(1)                                              BASH_BUILTINS(1)

NAME

       bash, :, ., [, alias, bg, bind, break, builtin, cd, command, compgen, complete, con-

       tinue, declare, dirs, disown, echo,  enable,  eval,  exec,  exit,  export,  fc,  fg,

       getopts,  hash,  help, history, jobs, kill, let, local, logout, popd, printf, pushd,

       pwd, read, readonly, return, set, shift, shopt, source, suspend, test, times,  trap,

       type,  typeset,  ulimit,  umask,  unalias, unset, wait - bash built-in commands, see

       bash(1)

[root@su250 ~]# help help

help: help [-s] [pattern ...]

    Display helpful information about builtin commands.  If PATTERN is

    specified, gives detailed help on all commands matching PATTERN,

    otherwise a list of the builtins is printed.  The -s option

    restricts the output for each builtin command matching PATTERN to

    a short usage synopsis.

[root@su250 ~]#

[root@su250 ~]# help umask

umask: umask [-p] [-S] [mode]

    The user file-creation mask is set to MODE.  If MODE is omitted, or if

    `-S' is supplied, the current value of the mask is printed.  The `-S'

    option makes the output symbolic; otherwise an octal number is output.

    If `-p' is supplied, and MODE is omitted, the output is in a form

    that may be used as input.  If MODE begins with a digit, it is

    interpreted as an octal number, otherwise it is a symbolic mode string

    like that accepted by chmod(1).

[root@su250 ~]#

[root@su250 ~]# help ulimit

ulimit: ulimit [-SHacdfilmnpqstuvx] [limit]

    Ulimit provides control over the resources available to processes

    started by the shell, on systems that allow such control.  If an

    option is given, it is interpreted as follows:

        -S      use the `soft' resource limit

        -H      use the `hard' resource limit

        -a      all current limits are reported

        -c      the maximum size of core files created

        -d      the maximum size of a process's data segment

        -e      the maximum scheduling priority (`nice')

        -f      the maximum size of files written by the shell and its children

        -i      the maximum number of pending signals

        -l      the maximum size a process may lock into memory

        -m      the maximum resident set size (has no effect on Linux)

        -n      the maximum number of open file descriptors

        -p      the pipe buffer size

        -q      the maximum number of bytes in POSIX message queues

        -r      the maximum real-time scheduling priority

        -s      the maximum stack size

        -t      the maximum amount of cpu time in seconds

        -u      the maximum number of user processes

        -v      the size of virtual memory

        -x      the maximum number of file locks

If LIMIT is given, it is the new value of the specified resource;

    the special LIMIT values `soft', `hard', and `unlimited' stand for

    the current soft limit, the current hard limit, and no limit, respectively.

    Otherwise, the current value of the specified resource is printed.

    If no option is given, then -f is assumed.  Values are in 1024-byte

    increments, except for -t, which is in seconds, -p, which is in

    increments of 512 bytes, and -u, which is an unscaled number of

    processes.

[root@su250 ~]#

[root@su250 ~]# help kill source

kill: kill [-s sigspec|-n signum | -sigspec] pid | jobspec ... or kill -l [sigspec]

    Send the processes named by PID (or JOBSPEC) the signal SIGSPEC.  If

    SIGSPEC is not present, then SIGTERM is assumed.  An argument of `-l'

    lists the signal names; if arguments follow `-l' they are assumed to

    be signal numbers for which names should be listed.  Kill is a shell

    builtin for two reasons: it allows job IDs to be used instead of

    process IDs, and, if you have reached the limit on processes that

    you can create, you don't have to start a process to kill another one.

source: source filename [arguments]

    Read and execute commands from FILENAME and return.  The pathnames

    in $PATH are used to find the directory containing FILENAME.  If any

    ARGUMENTS are supplied, they become the positional parameters when

    FILENAME is executed.

[root@su250 ~]#

[root@su250 ~]# ls -l /bin/find

-rwxr-xr-x 1 root root 161192 Apr 30  2008 /bin/find

[root@su250 ~]#

[root@su250 ~]# help find

-bash: help: no help topics match `find'.  Try `help help' or `man -k find' or `info find'.

[root@su250 ~]#