1,查看系统支持的shell类型：
[root@centos6 ~]# cat /etc/shells
/bin/sh
/bin/bash
/sbin/nologin
/bin/dash
/bin/tcsh
/bin/csh
2,查看我的系统用的是哪种shell类型：
[root@centos6 ~]# echo $SHELL
/bin/bash
[root@centos6 ~]#
3,查看完整的主机名称：
[root@centos6 ~]# echo $SHELL
/bin/bash
[root@centos6 ~]# //波浪符表示目前在哪个文件夹下
4,查看bash具体信息：
[root@centos6 ~]#ll /bin/bash
-rwxr-xr-x. 1 root root 906568 Mar 23 2017 /bin/bash #可以看到，bash大小有906568KB，里面集成了很多内部命令等文件
[root@centos6 ~]#ll /bin/ls
-rwxr-xr-x. 1 root root 109208 Mar 23 2017 /bin/ls #ls命令在bin下，是外部命令
5,查看全部内部命令：
方法一：
[root@centos6 ~]#enable
enable .
enable :
enable [
enable alias #从这里开始
enable bg
enable bind
enable break
enable builtin
enable caller
enable cd
enable command
enable compgen
enable complete
enable compopt
enable continue
enable declare
enable dirs
enable disown
enable echo
enable enable
enable eval
enable exec
enable exit
enable export
enable false
enable fc
enable fg
enable getopts
enable hash
enable help
enable history
enable jobs
enable kill
enable let
enable local
enable logout
enable mapfile
enable popd
enable printf
enable pushd
enable pwd
enable read
enable readarray
enable readonly
enable return
enable set
enable shift
enable shopt
enable source
enable suspend
enable test
enable times
enable trap
enable true
enable type
enable typeset
enable ulimit
enable umask
enable unalias
enable unset
enable wait
方法二：
[root@centos7 ~]# help
GNU bash, version 4.2.46(2)-release (x86_64-redhat-linux-gnu)
These shell commands are defined internally. Type `help' to see this list.
Type `help name' to find out more about the function `name'.
Use `info bash' to find out more about the shell in general.
Use `man -k' or `info' to find out more about commands not in this list.
A star (*) next to a name means that the command is disabled.
job_spec [&] history [-c] [-d offset] [n] or history -anrw [filename] or history -ps arg [arg...]
(( expression )) if COMMANDS; then COMMANDS; [ elif COMMANDS; then COMMANDS; ]... [ else COMMANDS; ] fi
. filename [arguments] jobs [-lnprs] [jobspec ...] or jobs -x command [args]
: kill [-s sigspec | -n signum | -sigspec] pid | jobspec ... or kill -l [sigspec]
[ arg... ] let arg [arg ...]
[[ expression ]] local [option] name[=value] ...
alias [-p] [name[=value] ... ] logout [n]
bg [job_spec ...] mapfile [-n count] [-O origin] [-s count] [-t] [-u fd] [-C callback] [-c quantum] [array]
bind [-lpvsPVS] [-m keymap] [-f filename] [-q name] [-u name] [-r keyseq] [-x keyseq:shell-c> popd [-n] [+N | -N]
break [n] printf [-v var] format [arguments]
builtin [shell-builtin [arg ...]] pushd [-n] [+N | -N | dir]
caller [expr] pwd [-LP]
case WORD in [PATTERN [| PATTERN]...) COMMANDS ;;]... esac read [-ers] [-a array] [-d delim] [-i text] [-n nchars] [-N nchars] [-p prompt] [-t timeout>
cd [-L|[-P [-e]]] [dir] readarray [-n count] [-O origin] [-s count] [-t] [-u fd] [-C callback] [-c quantum] [array]>
command [-pVv] command [arg ...] readonly [-aAf] [name[=value] ...] or readonly -p
compgen [-abcdefgjksuv] [-o option] [-A action] [-G globpat] [-W wordlist] [-F function] [> return [n]
complete [-abcdefgjksuv] [-pr] [-DE] [-o option] [-A action] [-G globpat] [-W wordlist] [-F> select NAME [in WORDS ... ;] do COMMANDS; done
compopt [-o|+o option] [-DE] [name ...] set [-abefhkmnptuvxBCHP] [-o option-name] [--] [arg ...]
continue [n] shift [n]
coproc [NAME] command [redirections] shopt [-pqsu] [-o] [optname ...]
declare [-aAfFgilrtux] [-p] [name[=value] ...] source filename [arguments]
dirs [-clpv] [+N] [-N] suspend [-f]
disown [-h] [-ar] [jobspec ...] test [expr]
echo [-neE] [arg ...] time [-p] pipeline
enable [-a] [-dnps] [-f filename] [name ...] times
eval [arg ...] trap [-lp] [[arg] signal_spec ...]
exec [-cl] [-a name] [command [arguments ...]] [redirection ...] true
exit [n] type [-afptP] name [name ...]
export [-fn] [name[=value] ...] or export -p typeset [-aAfFgilrtux] [-p] name[=value] ...
false ulimit [-SHacdefilmnpqrstuvx] [limit]
fc [-e ename] [-lnr] [first] [last] or fc -s [pat=rep] [command] umask [-p] [-S] [mode]
fg [job_spec] unalias [-a] name [name ...]
for NAME [in WORDS ... ] ; do COMMANDS; done unset [-f] [-v] [name ...]
for (( exp1; exp2; exp3 )); do COMMANDS; done until COMMANDS; do COMMANDS; done
function name { COMMANDS ; } or name () { COMMANDS ; } variables - Names and meanings of some shell variables
getopts optstring name [arg] wait [id]
hash [-lr] [-p pathname] [-dt] [name ...] while COMMANDS; do COMMANDS; done
help [-dms] [pattern ...] { COMMANDS ; }
6,查看某命令是外部命令还是内部命令：
[root@centos6 ~]#type cd
cd is a shell builtin #内部
[root@centos6 ~]#type ls
ls is aliased to `ls --color=auto' #外部
[root@centos6 ~]#type hostname
hostname is /bin/hostname #外部
[root@centos6 ~]#type type
type is a shell builtin #内部
[root@centos6 ~]#type enable
enable is a shell builtin #内部
注：内部命令保存在内存上，外部命令是磁盘文件，所以外部命令的执行效率不如内部命令
7,查看命令地址：
[root@centos6 ~]#which ls
alias ls='ls --color=auto'
/bin/ls
[root@centos6 ~]#whereis ls
ls: /bin/ls /usr/share/man/man1/ls.1.gz /usr/share/man/man1p/ls.1p.gz
#whereis命令显示的要比which命令更详细一些，不仅显示了该命令的所在路径，还显示了命令相关文档的路径
8,哈希表：将外部命令的路径保存到了哈希表中，下次执行时可以直接访问，下面是已经保存到哈希表中的路径
[root@centos6 ~]#hash
hits command
1 /usr/bin/whereis
2 /bin/ls
9,命令别名：用alias命令
[root@centos6 ~]#cd /etc/sysconfig/network-scripts/
[root@centos6 network-scripts]#cd
[root@centos6 ~]#alias cdnet="cd /etc/sysconfig/network-scripts/"
[root@centos6 ~]#cdnet
[root@centos6 ~]#nano .bashrc //把刚才做出的命令别名改动保存到系统文件中，使得重新登录系统时依然有效
# .bashrc
# User specific aliases and functions
alias rm='rm -i'
alias cp='cp -i'
alias mv='mv -i'
alias cdnet="cd /etc/sysconfig/network-scripts/" //将命令写入文件中，保存生效
# Source global definitions
if [ -f /etc/bashrc ]; then
. /etc/bashrc
fi
^G Get Help ^O WriteOut ^R Read File ^Y Prev Page ^K Cut Text ^C Cur Pos
^X Exit ^J Justify ^W Where Is ^V Next Page ^U UnCut Text ^T To Spell
[root@centos6 ~]. .bashrc //让别名立即生效
[root@centos6 ~]#unalias cdnet //取消别名
[root@centos6 ~]#cdnet
-bash: cdnet: command not found //取消别名生效
[root@centos6 ~]#alias //查看所有的命令别名
alias cp='cp -i'
alias l.='ls -d .* --color=auto'
alias ll='ls -l --color=auto'
alias ls='ls --color=auto'
alias mv='mv -i'
alias rm='rm -i'
alias which='alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde'
[root@centos6 ~]#
注：如果想永久有效，要定义在配置文件中
仅对当前用户：~/.bashrc
对所有用户有效：/etc/bashrc //上面的操作是对所有用户有效
10,让原始命令发挥作用的方法
[root@centos6 ~]#alias hostname="ls"
[root@centos6 ~]#hostname
anaconda-ks.cfg Documents install.log Music Public Videos
Desktop Downloads install.log.syslog Pictures Templates
[root@centos6 ~]#"hostname" //方法一
centos6.young.magedu
[root@centos6 ~]#'hostname' //方法二
centos6.young.magedu
[root@centos6 ~]#\hostname //方法三
centos6.young.magedu
[root@centos6 ~]#command hostname //方法四
centos6.young.magedu
[root@centos6 ~]#
注：命令别名要比原始命令的优先级高
11,查看时间：
[root@centos6 ~]#clock //主板上的时间，硬件时间
Thu 08 Mar 2018 11:13:09 AM CST -0.635436 seconds
[root@centos6 ~]#date //Linux内核时间
Thu Mar 8 11:13:15 CST 2018
[root@centos6 ~]#date 030811162018.30 //修改时间
Thu Mar 8 11:16:30 CST 2018
[root@centos6 ~]#clock -w //更新时间
[root@centos6 ~]#clock
Thu 08 Mar 2018 11:16:52 AM CST -0.876316 seconds
12,命令提示符：prompt
[root@localhost ~]#
注： “# ”表示管理员 “$”表示普通用户
[1]显示提示符格式
[root@centos7 ~]# echo $PS1
[\u@\h \W]\$
[2]修改提示符格式
PS1="\[\e[1;5;41;33m\][\u@\h \W]\\$\[\e[0m\]" 该命令提示符修改该后为红底黄字闪烁
\e \033 \u 当前用户
\h 主机名简称
\H 主机名
\w 当前工作目录
\W 当前工作目录基名
\t 24小时时间格式
\T 12小时时间格式
! 命令历史数
# 开机后命令历史数
[3] 保存修改后的提示符格式：
方法一、在虚拟机终端中输入命令
geit .bash_profile
进入图形化编辑页面，将PS1="\[\e[1;5;41;33m\][\u@\h \W]\\$\[\e[0m\]"输入进去，点击“Save”
方法二、输入命令：
nano .bash_profile
将上面命令复制进去保存
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