Linux基础之Shell脚本常用命令

#!/bin/sh

1 取脚本参数

$# 参数个数
$0 当前脚本名
$1 第1个参数
$n 第n个参数
$* 所有参数
$@ 所有参数
$? 上个命令的状态
$$ 当前pid

取当前目录

$(cd `dirname $0`; pwd)

2 日期

$ date
Wed Mar 27 17:27:18 CST 2019
$ date +"%Y-%m-%d %H:%M:%S"
2019-03-27 17:28:27
$ date +"%Y-%m-%d %H:%M:%S" --date="-1 day"
2019-03-26 17:29:10
$ date +%s
1553678982

$ date -d "-1day2019-05-20" +%Y%m%d
20190519

$ date -d"$(date -d"1 month" +"%Y%m01") -1 day" +"%Y%m%d"
20190531

$ date +"%Y%m$(cal|sed 'N;${s/.* //;P;d};D')"
20190531

3 字符串替换

将变量var中的a全部替换成b

${var//a/b}
echo "$var"|awk 'gsub("a","b") {print $0}'
echo "$"|sed 's/a/b/'

4 字符串截取子串

var=hello
echo ${#var}
echo $var|awk '{print substr($0, 2, 3)}'
echo ${var:2}
echo ${var:2:3}

echo ${var#he}
echo ${var%lo}

echo ${var1:`echo $((${#var2}+1))`}

5 字符串split

数组(item本身不能包含空格)

str=${str//,/ }
for item in $str 
do
    echo $item
done

cut(cut: the delimiter must be a single character 分隔符只能为1个字符)

        i=1
        while((1==1))
        do
                item=`echo $str|cut -d "," -f$i`
                if [ "$item" != "" ]
                then
                        ((i++))
                        echo $item
                else
                        break
                fi
        done

awk -F(索引位置只能硬编码)

$ echo $str|awk -F ',' '{print $1}

awk split

$ echo $str|awk '{split($0,arr,","); for (i in arr) {print arr[i]}}'

6 循环

字符串循环(空格分割)

var='1 2 3'
for var in $vars
do
echo $var
done

整数循环(从1到100)

for i in {1..100}
do
echo $i
done

自增id

i=0
for var in $vars
do
echo "$i $var"
((i=i+1))
done

while

#while true
while [ 1 -eq 1 ]
do
..
break/continue
..
done

7 字符串是否为空判断(相等、不等)

if [ -z "$var" ]
then
echo "var is empty"
fi

if [ -n "$var" ]
then
echo "var is not empty"
fi

if [[ "$var" = "" ]]
then
echo "empty"
fi

if [[ "$var" != "" ]]
then
echo "not empty"
fi

8 字符串包含判断

if [[ "$all" == *"$sub"* ]]; then

or

if [[ "$all" =~ "$sub" ]] ;then

9 整数比较判断

if [ $a -eq 0 ]
then
echo "a = 0"
fi

if [ $a -ne 0 ]
then
echo "a != 0"
fi

if [ $a -gt 0 ]
then
echo "a > 0"
fi

if [ $a -lt 0 ]
then
echo "a < 0"
fi

10 if

if-else

if cond; then

...

elif cond; then

...

else

...

fi

布尔连接AND OR

if [ $a -lt 0 -a -z "$b" ]; then

  echo ''

fi

或者

if [ $a -lt 0 ] && [ -z "$b" ]; then

  echo ''

fi

以上为AND,替换 -a -> -o, && -> || 后为OR

11 整数计算

echo $((2+1))

12 注释

单行注释

# comment

多行注释

<<'COMMENT'
comment1
comment2
...
COMMENT

13 文件和文件夹判断

if [ -d "/path/to/dir" ]
then
echo 'directory /path/to/dir exists'
else
echo 'directory /path/to/dir does not exists'
fi

if [ -f "/path/to/file" ]
then
echo 'file /path/to/file exists'
else
echo 'file /path/to/file does not exists'
fi

14 遍历文件夹

dir=/path/to/dir/
for file in $dir/*
do
echo $file
done

15 退出脚本

exit 0
exit 1

 

posted @ 2019-02-22 11:13  匠人先生  阅读(473)  评论(0编辑  收藏  举报