assert_perror - Linux


assert_perror is a utility for simulating permission errors. It executes a command with certain file permissions denied, allowing users to test error-handling code and observe its behavior.


assert_perror [options] <command> <args>


  • -d, –dir Deny directory permissions.
  • -f, –file Deny file permissions.
  • -r, –read Deny read permission.
  • -w, –write Deny write permission.
  • -x, –execute Deny execute permission.
  • -q, –quiet Suppress non-error output.
  • -p, –pattern Use a pattern to filter output.
  • -h, –help Display help message.


Testing read permission:

assert_perror -r cat /etc/passwd

Testing multiple permissions with a quiet output:

assert_perror -dwqxq echo "Hello world" > /myfile

Filtering output with a pattern:

assert_perror -p 'Permission denied' echo "Hello world" > /myfile

Common Issues

  • Ensure that the correct permissions are being denied.
  • Verify that the specified file or directory exists.
  • Use the --quiet option to suppress non-error output.


assert_perror can be integrated into test scripts to simulate specific error scenarios. It can also be used in conjunction with other commands for advanced error testing.

Related Commands

  • perror
  • test
  • mock