快速参考
https://quickref.cn/docs/bash.html#bash-%E5%87%BD%E6%95%B0
入门
hello.sh
#!/bin/bash
VAR="world"
echo "Hello $VAR!" # => Hello world!
执行脚本
$ bash hello.sh
变量
NAME="John"
echo ${NAME} # => John (变量)
echo $NAME # => John (变量)
echo "$NAME" # => John (变量)
echo '$NAME' # => $NAME (字符串原样输出)
echo "${NAME}!" # => John! (变量)
NAME = "John" # => Error (注意不能有空格)
注释-Comments
# This is an inline Bash comment.
: '
This is a
very neat comment
in bash
'
多行注释使用 :’ 打开和 ‘ 关闭
参数Arguments
| 序号 | 名称 |
|---|---|
| $1 | … $9 Parameter 1 … 9 |
| $0 | Name of the script itself |
| $1 | First argument |
| ${10} | Positional parameter 10 |
| $# | Number of arguments |
| $$ | Process id of the shell |
| $* | All arguments |
| $@ | All arguments, starting from first |
| $- | Current options |
| $_ | Last argument of the previous command |
函数 Functions
get_name() {
echo "John"
}
echo "You are $(get_name)"
条件句
if [[ -z "$string" ]]; then
echo "String is empty"
elif [[ -n "$string" ]]; then
echo "String is not empty"
fi
大括号扩展
echo {A,B}.js
| 序号 | 描述 |
|---|---|
| {A,B} | Same as A B |
| {A,B}.js | Same as A.js B.js |
| {1..5} | Same as 1 2 3 4 5 |
Shell执行
# => I'm in /path/of/current
echo "I'm in $(PWD)"
# Same as:
echo "I'm in `pwd`"