查看当前设备终端
# tty
/dev/pts/0
显示当前使用的shell
# echo ${SHELL}
/bin/bash
显示当前使用所使用的所有shell
# cat /etc/shells
/bin/sh
/bin/bash
/sbin/nologin
/bin/dash
/bin/tcsh
/bin/csh
查看命令
# which ls
alias ls='ls --color=auto'
/bin/ls
查看命令是内部还是外部命令
# type ls
ls is aliased to `ls --color=auto'
# type cat
cat is hashed (/bin/cat)
查看命令位置
# whereis ls
ls: /bin/ls /usr/share/man/man1/ls.1.gz /usr/share/man/man1p/ls.1p.gz
查看命令man文件
#whatis ls
ls (1) - list directory contents
ls (1p) - list directory contents
# man 1p ls
# man 1 ls