|||
注意一下两条命令,结果不一样,以前没有理解。
[root@guohuiqiang /]# cd /root
[root@guohuiqiang~]# ls
~]# aaa aaa.txt Desktop err.out install.log Music Public Videos
2014zuihouyiwang.log aaaa all.log Documents guo install.log.syslog new_file sss.log
2.log aaa.log anaconda-ks.cfg Downloads guo.log mkfs.ext Pictures Templates
[root@guohuiqiang ~]# cd /
[root@guohuiqiang/]# ls
bin dev guohuiqiang lib mbr mnt passwd pub root selinux strong sys usr
boot etc home lost+found media opt proc public sbin srv strong[root@localhost tmp var
[root@guohuiqiang /]# cd /root
[root@guohuiqiang~]# ls -a
~]# aaa.txt .config .gconf guo.log .nautilus .tcshrc
. all.log .cshrc .gconfd .gvfs new_file Templates
.. anaconda-ks.cfg .dbus .gnome2 .ICEauthority Pictures Videos
2014zuihouyiwang.log .bash_history Desktop .gnote install.log Public .viminfo
2.log .bash_logout Documents .gnupg install.log.syslog .pulse
aaa .bash_profile Downloads .gstreamer-0.10 .local .pulse-cookie
aaaa .bashrc err.out .gtk-bookmarks mkfs.ext .ssh
aaa.log .cache .esd_auth guo Music sss.log
root下面有个.bash_history的文件,不是根目录
[root@guohuiqiang~]# history
我们发现有超过1000命令历史,超过1000的部分存在内存中,如果终端非正常退出,则这些命令不会写入到.bash_history文件中。
999 init 0
1000 cd/root
1001 ls
1002 ls.
1003 ls-a
1004 history
1005 ls.
1006 less !
1007 ls.bash_history
1008 less .bash_history
1009 tail .bash_history
1010 history
[root@guohuiqiang~]# history –c (clear)
(清空了内存中命令历史,不会清空.bash_history文件中的命令)
[root@guohuiqiang~]# history
13 history
[root@guohuiqiang~]# history
13 history
14 cat .bash_history
15 history
[root@guohuiqiang ~]# !13(执行13的那条命令)
history
13 history
14 cat .bash_history
15 history
[root@guohuiqiang ~]# !$ (!$执行上一条命令)
history
13 history
14 cat .bash_history
15 history
[root@guohuiqiang~]# !ca
[root@guohuiqiang ~]# ls *.txt(*表示通配)
aaa.txt
[root@guohuiqiang ~]# env
HOSTNAME=guohuiqiang.com
SELINUX_ROLE_REQUESTED=
TERM=xterm
SHELL=/bin/bash
HISTSIZE=1000
SSH_CLIENT=192.168.88.149885 22
SELINUX_USE_CURRENT_RANGE=
OLDPWD=/root
SSH_TTY=/dev/pts/0
USER=root
LS_COLORS=rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:mi=01;05;37;41:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arj=01;31:*.taz=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.zip=01;31:*.z=01;31:*.Z=01;31:*.dz=01;31:*.gz=01;31:*.lz=01;31:*.xz=01;31:*.bz2=01;31:*.tbz=01;31:*.tbz2=01;31:*.bz=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.rar=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.jpg=01;35:*.jpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.axv=01;35:*.anx=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=01;36:*.au=01;36:*.flac=01;36:*.mid=01;36:*.midi=01;36:*.mka=01;36:*.mp3=01;36:*.mpc=01;36:*.ogg=01;36:*.ra=01;36:*.wav=01;36:*.axa=01;36:*.oga=01;36:*.spx=01;36:*.xspf=01;36:
MAIL=/var/spool/mail/root
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin
PWD=/root
LANG=en_US.UTF-8
SELINUX_LEVEL_REQUESTED=
SSH_ASKPASS=/usr/libexec/openssh/gnome-ssh-askpass
HISTCONTROL=ignoredups
SHLVL=1
HOME=/root
LOGNAME=root
SSH_CONNECTION=192.168.88.149885 192.168.88.131 22
LESSOPEN=|/usr/bin/lesspipe.sh%s
G_BROKEN_FILENAMES=1
_=/bin/env
声明一个全局变量
[root@guohuiqiang~]# export a=1(只在当前shell里面有效)
[root@guohuiqiang~]# b=2
[root@guohuiqiang~]# bash
[root@guohuiqiang~]# echo $b
另一个命令,set,显示的更全面
[root@guohuiqiang ~]# set
BASH=/bin/bash
BASHOPTS=checkwinsize:cmdhist:expand_aliases:extquote:force_fignore:hostcomplete:i nteractive_comments:progcomp:promptvars:sourcepath
BASH_ALIASES=()
BASH_ARGC=()
BASH_ARGV=()
BASH_CMDS=()
BASH_LINENO=()
BASH_SOURCE=()
BASH_VERSINFO=([0]="4"[1]="1" [2]="2" [3]="1" [4]="release"[5]="i386-redhat-linu x-gnu")
BASH_VERSION='4.1.2(1)-release'
COLORS=/etc/DIR_COLORS
COLUMNS=82
DIRSTACK=()
EUID=0
GROUPS=()
G_BROKEN_FILENAMES=1
HISTCONTROL=ignoredups
HISTFILE=/root/.bash_history
HISTFILESIZE=1000
HISTSIZE=1000
HOME=/root
HOSTNAME=guohuiqiang.com
HOSTTYPE=i386
ID=0
IFS=$'\t\n'
LANG=en_US.UTF-8
LESSOPEN='|/usr/bin/lesspipe.sh%s'
LINES=43
LOGNAME=root
LS_COLORS='rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd= 40;33;01:or=40;31;01:mi=01;05;37;41:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:s t=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arj=01;31:*.taz=01;31:*.lzh=01;31:*.lzm a=01;31:*.tlz=01;31:*.txz=01;31:*.zip=01;31:*.z=01;31:*.Z=01;31:*.dz=01;31:*.gz=01 ;31:*.lz=01;31:*.xz=01;31:*.bz2=01;31:*.tbz=01;31:*.tbz2=01;31:*.bz=01;31:*.tz=01; 31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.rar=01;31:*.ace=01;31:*.zoo=01;31:*.cpio= 01;31:*.7z=01;31:*.rz=01;31:*.jpg=01;35:*.jpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm =01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.t iff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35 :*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01 ;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=0 1;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl= 01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.axv=01;35:*.an x=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=01;36:*.au=01;36:*.flac=01;36:*.mid=01;36:*. midi=01;36:*.mka=01;36:*.mp3=01;36:*.mpc=01;36:*.ogg=01;36:*.ra=01;36:*.wav=01;36: *.axa=01;36:*.oga=01;36:*.spx=01;36:*.xspf=01;36:'
MACHTYPE=i386-redhat-linux-gnu
MAIL=/var/spool/mail/root
MAILCHECK=60
OPTERR=1
OPTIND=1
OSTYPE=linux-gnu
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin
PIPESTATUS=([0]="0")
PPID=2284
PROMPT_COMMAND='printf"\033]0;%s@%s:%s\007" "${USER}" "${HOSTNAME%%.*}""${PWD/#$ HOME/~}"'
PS1='[\u@\h\W]\$ '
PS2='>'
PS4='+'
PWD=/root
SELINUX_LEVEL_REQUESTED=
SELINUX_ROLE_REQUESTED=
SELINUX_USE_CURRENT_RANGE=
SHELL=/bin/bash
SHELLOPTS=braceexpand:emacs:hashall:histexpand:history:interactive-comments:monito r
SHLVL=2
SSH_ASKPASS=/usr/libexec/openssh/gnome-ssh-askpass
SSH_CLIENT='192.168.88.149885 22'
SSH_CONNECTION='192.168.88.149885 192.168.88.131 22'
SSH_TTY=/dev/pts/0
TERM=xterm
UID=0
USER=root
_=bash
a=1
colors=/etc/DIR_COLORS
__udisks()
{
local IFS='
';
localcur="${COMP_WORDS[COMP_CWORD]}";
if [ "${COMP_WORDS[$(($COMP_CWORD -1))]}" = "--show-info" ]; then
COMPREPLY=($(compgen -W "$(udisks--enumerate-device-files)" -- $cur));
else
if [ "${COMP_WORDS[$(($COMP_CWORD- 1))]}" = "--inhibit-polling" ]; then
COMPREPLY=($(compgen -W"$(udisks --enumerate-device-files)" -- $cur)) ;
else
if ["${COMP_WORDS[$(($COMP_CWORD - 1))]}" = "--mount" ]; then
COMPREPLY=($(compgen -W"$(udisks --enumerate-device-files)" -- $c ur));
else
if ["${COMP_WORDS[$(($COMP_CWORD - 1))]}" = "--unmount" ]; then
COMPREPLY=($(compgen -W"$(udisks --enumerate-device-files)" - - $cur));
else
if ["${COMP_WORDS[$(($COMP_CWORD - 1))]}" = "--detach" ];the n
COMPREPLY=($(compgen -W"$(udisks --enumerate-device-files )" -- $cur));
else
if ["${COMP_WORDS[$(($COMP_CWORD - 1))]}" = "--ata-smart- refresh" ]; then
COMPREPLY=($(compgen -W "$(udisks --enumerate-device-f iles)" -- $cur));
else
if ["${COMP_WORDS[$(($COMP_CWORD - 1))]}" = "--ata-sm art-simulate" ]; then
_filedir ||return 0;
else
if ["${COMP_WORDS[$(($COMP_CWORD - 1))]}" = "--se t-spindown" ]; then
COMPREPLY=($(compgen -W "$(udisks --enumerate- device-files)" -- $cur));
else
if ["${COMP_WORDS[$(($COMP_CWORD - 1))]}" = " --poll-for-media" ]; then
COMPREPLY=($(compgen -W "$(udisks --enumer ate-device-files)" -- $cur));
else
COMPREPLY=($(IFS=: compgen -W "--dump:--in hibit-polling:--inhibit-all-polling:--enumerate:--enumerate-device-files:--monitor :--monitor-detail:--show-info:--help:--mount:--mount-fstype:--mount-options:--unmo unt:--unmount-options:--detach:--detach-options:--ata-smart-refresh:--ata-smart-wa keup:--ata-smart-simulate:--set-spindown:--set-spindown-all:--spindown-timeout:--p oll-for-media" -- $cur));
fi;
fi;
fi;
fi;
fi;
fi;
fi;
fi;
fi
}
怎么定义一个变量名:
[root@guohuiqiang~]# a = 1 (不能有空格,变量名:英文数字下划线)
bash:a: command not found
[root@guohuiqiang~]# a=123
[root@guohuiqiang ~]# b=$a"4"
[root@guohuiqiang~]# echo b
b
[root@guohuiqiang~]# echo $b
1234
[root@guohuiqiang~]# echo $b
1234
[root@guohuiqiang~]# a=123;b=4
[root@guohuiqiang ~]# c=$a$b
[root@guohuiqiang~]# echo c
c
[root@guohuiqiang~]# echo $c
1234
[root@guohuiqiang ~]# a=2
[root@guohuiqiang ~]# echo $a
2
[root@guohuiqiang ~]# bash
[root@guohuiqiang ~]# echo $a
2
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