详解参数扩展
${parameter:-word}
1 | [root@vm-101 ~]# unset a |
${parameter:=word}
1 | [root@vm-101 ~]# unset a |
${parameter:?word}
1 | [root@vm-101 ~]# unset a |
${parameter:+word}
1 | [root@vm-101 ~]# unset a |
${parameter:offset}
${parameter:offset:length}
1 | [root@vm-101 ~]# a=123456 |
${!prefix*}
${!prefix@}
1 | [root@vm-101 ~]# cat a.sh |
${!name[@]}
${!name[*]}
1 | [root@vm-101 ~]# list=(11 22 33) |
${\#parameter}
变量值长度
1 | [root@vm-101 ~]# a=123456 |
${parameter#word}
${parameter##word}
1 | [root@vm-101 ~]# a="aaabbbcccddd" |
${parameter%word}
${parameter%%word}
1 | [root@vm-101 ~]# a="aaabbbcccddd" |
${parameter/pattern/string}
1 | [root@vm-101 ~]# a="hello,world" |
${parameter^pattern}
${parameter^^pattern}
${parameter,pattern}
${parameter,,pattern}
1 | [root@vm-101 ~]# a="abCdEfg" |