常用命令

help

输入：
help help
输出：

help: help [-dms] [pattern ...]

Display information about builtin commands.

Displays brief summaries of builtin commands.  If PATTERN is
specified, gives detailed help on all commands matching PATTERN,
otherwise the list of help topics is printed.

Options:
  -d    output short description for each topic
  -m    display usage in pseudo-manpage format
  -s    output only a short usage synopsis for each topic matching
    PATTERN

Arguments:
  PATTERN   Pattern specifiying a help topic

Exit Status:
Returns success unless PATTERN is not found or an invalid option is given.

options:
-d:输出简单描述
-m:用pesudo-manpage 格式输出用法指南
-s:只输出一个简单的用法梗概

bg

bg: bg [job_spec ...]

Move jobs to the background.

Place the jobs identified by each JOB_SPEC in the background, as if they
had been started with `&'.  If JOB_SPEC is not present, the shell's notion
of the current job is used.

Exit Status:
Returns success unless job control is not enabled or an error occurs.

bind

bind: bind [-lpsvPSVX] [-m keymap] [-f filename] [-q name] [-u name] [-r keyseq] [-x keyseq:shell-command] [keyseq:readline-function or readline-command]

Set Readline key bindings and variables.

Bind a key sequence to a Readline function or a macro, or set a
Readline variable.  The non-option argument syntax is equivalent to
that found in ~/.inputrc, but must be passed as a single argument:
e.g., bind '"\C-x\C-r": re-read-init-file'.

Options:
  -m  keymap         Use KEYMAP as the keymap for the duration of this
                     command.  Acceptable keymap names are emacs,
                     emacs-standard, emacs-meta, emacs-ctlx, vi, vi-move,
                     vi-command, and vi-insert.
  -l                 List names of functions.
  -P                 List function names and bindings.
  -p                 List functions and bindings in a form that can be
                     reused as input.
  -S                 List key sequences that invoke macros and their values
  -s                 List key sequences that invoke macros and their values
                     in a form that can be reused as input.
  -V                 List variable names and values
  -v                 List variable names and values in a form that can
                     be reused as input.
  -q  function-name  Query about which keys invoke the named function.
  -u  function-name  Unbind all keys which are bound to the named function.
  -r  keyseq         Remove the binding for KEYSEQ.
  -f  filename       Read key bindings from FILENAME.
  -x  keyseq:shell-command  Cause SHELL-COMMAND to be executed when
                KEYSEQ is entered.
  -X             List key sequences bound with -x and associated commands
                     in a form that can be reused as input.

Exit Status:
bind returns 0 unless an unrecognized option is given or an error occurs.

break

break: break [n]

Exit for, while, or until loops.

Exit a FOR, WHILE or UNTIL loop.  If N is specified, break N enclosing
loops.

Exit Status:
The exit status is 0 unless N is not greater than or equal to 1.

builtin

builtin: builtin [shell-builtin [arg ...]]

Execute shell builtins.

Execute SHELL-BUILTIN with arguments ARGs without performing command
lookup.  This is useful when you wish to reimplement a shell builtin
as a shell function, but need to execute the builtin within the function.

Exit Status:
Returns the exit status of SHELL-BUILTIN, or false if SHELL-BUILTIN is
not a shell builtin..