shell字符串截取报错:Bad substitution的解决

问题重现: 当前系统Ubuntu16 shell进行字符串截取 运行 ${GIT_COMMIT:0:6}报错: /tmp/jenkins7505855461406722507.sh: 4: /tmp/jenkins7505855461406722507.sh: Bad substitution 原因:两种shell语言解释器 bash和dash 查看当前/bin/sh 指向哪种解释器: ls /bin/sh -al lrwxrwxrwx 1 root root 4 Mar 26 2018 /bin/sh -> dash 修改bin/sh指向为bash: sudo ln -fs /b