帮助命令
适用内部命令
# type cd
cd is a shell builtin
# help cd
# type ls
ls is aliased to `ls --color=auto'
# help ls
-bash: help: no help topics match `ls'. Try `help help' or `man -k ls' or `info ls'.
cd is a shell builtin
# help cd
# type ls
ls is aliased to `ls --color=auto'
# help ls
-bash: help: no help topics match `ls'. Try `help help' or `man -k ls' or `info ls'.
适用外部命令：
ls --help
man 命令
看懂man命令语法
[]：可选内容
<>：必须给出内容
a|b|c：多选一
…：可以有多个
[]：可选内容
<>：必须给出内容
a|b|c：多选一
…：可以有多个