stringbashubuntusubstitution

bash: Bad Substitution

#!/bin/bash

jobname="job_201312161447_0003"
jobname_pre=${jobname:0:16}
jobname_post=${jobname:17}

This bash script gives me Bad substitution error on Ubuntu. Any help will be highly appreciated.

Solution

  • The default shell (/bin/sh) under Ubuntu points to dash, not bash.

    me@pc:~$ readlink -f $(which sh)
/bin/dash

    So if you chmod +x your_script_file.sh and then run it with ./your_script_file.sh, or if you run it with bash your_script_file.sh, it should work fine.

    Running it with sh your_script_file.sh will not work because the hashbang line will be ignored and the script will be interpreted by dash, which does not support that string substitution syntax.