命令
- 1: colon
 - 2: 1dot
 - 3: 3dot
 - 4: trap
 - 5: cancel
 - 6: lprm
 - 7: lpq
 - 8: lpstat
 - 9: lp
 - 10: lpr
 - 11: groff
 - 12: roff
 - 13: printf
 - 14: pr
 - 15: fmt
 - 16: fold
 - 17: nl
 - 18: aspell
 - 19: sed
 - 20: tr
 - 21: patch
 - 22: diff
 - 23: comm
 - 24: join
 - 25: paste
 - 26: cut
 - 27: sort
 - 28: cat
 - 29: rsync
 - 30: zip
 - 31: tar
 - 32: bzip2
 - 33: gzip
 - 34: find
 - 35: locate
 - 36: sftp
 - 37: scp
 - 38: ssh
 - 39: wget
 - 40: lftp
 - 41: ftp
 - 42: netstat
 - 43: traceroute
 - 44: ping
 - 45: killall
 - 46: kill
 - 47: top
 - 48: ps
 - 49: chgrp
 - 50: chown
 - 51: sudo
 - 52: su
 - 53: umask
 - 54: chmod
 - 55: tee
 - 56: tail
 - 57: head
 - 58: grep
 - 59: wc
 - 60: uniq
 - 61: info
 - 62: whatis
 - 63: apropos
 - 64: man
 - 65: help
 - 66: which
 - 67: type
 - 68: ln
 - 69: rm
 - 70: mv
 - 71: cp
 - 72: mkdir
 - 73: less
 - 74: file
 - 75: ls
 
1 - colon
- NAME
 - Null command.
 
SYNOPSIS :
DESCRIPTION Null command.
No effect; the command does nothing.
Exit Status:
Always succeeds.
SEE ALSO bash(1)
IMPLEMENTATION GNU bash, version 5.0.17(1)-release (x86_64-redhat-linux-gnu) Copyright (C) 2019 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later http://gnu.org/licenses/gpl.html
2 - 1dot
https://linuxcommand.org/lc3_man_pages/doth.html
NAME . - Execute commands from a file in the current shell.
SYNOPSIS . filename [arguments]
DESCRIPTION Execute commands from a file in the current shell.
Read and execute commands from FILENAME in the current shell.  The
entries in $PATH are used to find the directory containing FILENAME.
If any ARGUMENTS are supplied, they become the positional parameters
when FILENAME is executed.
Exit Status:
Returns the status of the last command executed in FILENAME; fails if
FILENAME cannot be read.
SEE ALSO bash(1)
IMPLEMENTATION GNU bash, version 5.0.17(1)-release (x86_64-redhat-linux-gnu) Copyright (C) 2019 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later http://gnu.org/licenses/gpl.html
3 - 3dot
https://linuxcommand.org/lc3_man_pages/dbl_parensh.html
NAME (( … )) - Evaluate arithmetic expression.
SYNOPSIS (( expression ))
DESCRIPTION Evaluate arithmetic expression.
The EXPRESSION is evaluated according to the rules for arithmetic
evaluation.  Equivalent to "let EXPRESSION".
Exit Status:
Returns 1 if EXPRESSION evaluates to 0; returns 0 otherwise.
SEE ALSO bash(1)
IMPLEMENTATION GNU bash, version 5.0.17(1)-release (x86_64-redhat-linux-gnu) Copyright (C) 2019 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later http://gnu.org/licenses/gpl.html