the basic shell skills.
- Bourne shell
-
- sh
- ksh
- Bash
- psh
- zsh
- C shell
-
- csh
- tcsh
[root@bogon temp]# cat /etc/shells
/bin/sh
/bin/bash
/sbin/nologin
/usr/bin/sh
/usr/bin/bash
/usr/sbin/nologin
/bin/tcsh
/bin/csh
1.echo
[root@bogon temp]# echo "hello world!"
-bash: !": event not found
[root@bogon temp]# echo 'hello world!'
hello world!
2.sh
sh script must declare #!/bin/bash at the begining
you'd better show note
[root@bogon sh]# cat -A hello.sh
#!/bin/bash$
#Ryan$
$
echo "Hello World"$
cat -A will print all character include \n. You can see, my script hava a $, this is the \n in linux, if in windows, it will be ^M$, you have to run dos2unix to convert it.
3.Basis
3.1.history
show the history command you had typed
history
!n --execute the num n
!! --execute the laste , acturelly, we use ↑
3.2.alias
[root@bogon sh]# alias
alias cp='cp -i'
alias egrep='egrep --color=auto'
alias fgrep='fgrep --color=auto'
alias grep='grep --color=auto'
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 vi='vim'
alias which='alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde'
3.3 shortcuts
ctrl+A move to line start
ctrl+E move to line end
ctrl+C stop
ctrl+L clean
ctrl+U delete the command before the cursor
ctrl+K delete the command after the cursor
ctrl+Y paste the command that you ctrl+U/K
ctrl+R search from history
ctrl+D exit
ctrl+Z suspend and background
4.command
ls -a /etc/ | more
grep
-i ingnore case
-n show linenum
-v negate
var
- =bothends can't be space
- $var_name, ${varname}
- `` ==$()
envrionment
parent-shell->sub-shell
export var_name=var_value
env
unset var_name
source profile, . ./profile
- /etc/profile
- /etc/profile.d/*.sh
- ~/.bash_profile
- ~/.bashrc
- /etc/bashrc
| ? | one |
| * | any |
| [] | the char inside[] |
| [-] | the char in the range of [-] |
| [^] | the opposite char |
| '' | anything is char |
| "" | double quotation, specific char like "$"、"`"、"\" |
| `` | ==$() |
| $() | command to be var |
| # | note |
| \ | transfferred meaning |
var position
| $n | $0-command itselt; $1-$9 the attr after command; beyond 10 ${10} |
| $* | all attrs as a attr |
| $@ | all attrs as attrs |
| $# | the sum of attrs |
| $? | the status of the last command : 0? correct:error |
| $$ | current PID |
| $! | last PID in backgroud |
read -t 30 -p "please input somethind :" sm
echo $sm
caculate num
- declare -i cc=$aa+$bb
- dd=$(expr $aa + $bb)
- ff=$(($aa+$bb))
regular
| * | behind char any times |
| . | one char |
| ^ | begin |
| $ | end |
| [] | any inside char |
| [^] | can be inside char |
| \ | transfer |
| \{n\} | n times behind. [0-9]\{4\} ~ 1234; [1][3-8][0-9]\{9\} ~ tel |
| \{n,\} | at least n times |
| \{n,m\} | at least n times and at most m times |
| .* | any char any times |
| \.$ | end with . |
output
command >file cover
command >>file append
err command 2>file
err command2>>file
command>file 2>&1
command &>> file
char cut
cut
-d seperator
-f the index
[root@00:09:13 /temp/project/sh]$ cut -d ":" -f 1,3 /etc/passwd
root:0
bin:1
[root@00:13:16 /temp/project/sh]$ cat /etc/passwd | grep /bin/bash | grep -v root | cut -d ":" -f 1,3
amandabackup:33
ryan:1000
yue:1001
yangmi:1002
bimm:1003
cangls:1004
st:1005
printf
%ns: n char
%ni: n num
%m.nf 12.34
awk
awk [POSIX or GNU style options] -f progfile [--] file ...
[root@00:24:15 /temp/project/sh]$ cat stu.txt
name age aa
mrf 12 bb
ryan 18 vv
[root@00:24:31 /temp/project/sh]$ awk '{printf $2 "\t" $3 "\n"} ' stu.txt
age aa
12 bb
18 vv
[root@00:24:33 /temp/project/sh]$ df -h | awk '{print $1 "\t" $5 "\t" $6}'
[root@00:29:04 /temp/project/sh]$ df -h
文件系统 容量 已用 可用 已用% 挂载点
/dev/mapper/centos-root 50G 5.3G 45G 11% /
devtmpfs 1.6G 0 1.6G 0% /dev
tmpfs 1.6G 0 1.6G 0% /dev/shm
tmpfs 1.6G 9.0M 1.6G 1% /run
tmpfs 1.6G 0 1.6G 0% /sys/fs/cgroup
/dev/mapper/centos-home 278G 37M 278G 1% /home
/dev/sda6 497M 162M 335M 33% /boot
tmpfs 327M 0 327M 0% /run/user/0
[root@00:29:12 /temp/project/sh]$ df -h | grep root | awk '{print $5}' | cut -d "%" -f111
sed
change the file line2
sed -i '2c theReplaceMsg' file
p printf
d delte
a append
i insert
c replace line
s sed 'ns/old/new/g' file
if
[root@bogon sh]# [ "$aa"=="$bb" ] && echo yes || echo no
yes
-n var_name if var_name!=null return true
-z var_name if var_name==null return true
! var_name opposite
if [ ] ;then
....
elif [ ]
then
...
else
...
fi
or
if [ ]
then
.....
fi
case
case $var_name in
val1)
...
;;
val2)
...
;;
*)
...
;;
esac
for
for var_name in val1 val2 val3 ...
do
..
done
while
while [ $i -le 100 ]
do
...
done
5.Other
ps
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 0.0 0.1 41632 4060 ? Ss 5月13 0:12 /usr/lib/systemd/systemd --switched-root --system --deserialize 21
root 2 0.0 0.0 0 0 ? S 5月13 0:00 [kthreadd]
root 3 0.0 0.0 0 0 ? S 5月13 0:05 [ksoftirqd/0]
root 7 0.0 0.0 0 0 ? S 5月13 0:00 [migration/0]
root 8 0.0 0.0 0 0 ? S 5月13 0:00 [rcu_bh]
root 9 0.0 0.0 0 0 ? S 5月13 0:00 [rcuob/0]
root 10 0.0 0.0 0 0 ? S 5月13 0:00 [rcuob/1]
root 11 0.0 0.0 0 0 ? S 5月13 0:00 [rcuob/2]
root 12 0.0 0.0 0 0 ? S 5月13 0:00 [rcuob/3]
root 13 0.0 0.0 0 0 ? S 5月13 4:18 [rcu_sched]
top
kill
kill -1 restart
kill -9 pid (force)
kill 15 pid (default)
crond
crontab -e
唯有不断学习方能改变！ -- Ryan Miao
