shell截取字符串

获取字符串长度

str=Alan
echo ${#str}
# 4

最小限度从前面截取字符串

str=https://www.runoob.com/linux/linux-shell-passing-arguments.html
echo ${str#*/}
# /www.runoob.com/linux/linux-shell-passing-arguments.html

最大限度从前面截取字符串

str=https://www.runoob.com/linux/linux-shell-passing-arguments.html
echo ${str##*/}
# linux-shell-passing-arguments.html

最小限度从后面截取字符串

str=https://www.runoob.com/linux/linux-shell-passing-arguments.html
echo ${str%/*}
# https://www.runoob.com/linux

最大限度从后面截取字符串

str=https://www.runoob.com/linux/linux-shell-passing-arguments.html
echo ${str%%/*}
# https:

使用${var:} 模式获取子字符串

语法：

${var:start:len}

str=https://www.runoob.com/linux/linux-shell-passing-arguments.html
echo ${str:0:6}
# https:

从左边第几个字符开始一直到结束

语法：

${var:start}

str=https://www.runoob.com/linux/linux-shell-passing-arguments.html
echo ${str:6}
# //www.runoob.com/linux/linux-shell-passing-arguments.html

从右边第几个字符开始以及字符的个数

语法：

${var:0-start:len}

str=https://www.runoob.com/linux/linux-shell-passing-arguments.html
echo ${str:0-15:5}
# -argu

从右边第几个字符开始一直到结束

语法：

${var:0-start}

str=https://www.runoob.com/linux/linux-shell-passing-arguments.html
echo ${str:0-15}
# -arguments.html