The man page has a section titled "Exit On Error Behavior" which talks about instructing 'guestfish' to ignore errors from commands in non-interactive mode by prefixing a '-' character to the command generating the error. In my case, I was trying to ignore an error from the 'mount' command like so: $ guestfish add rhel-guest-image-6.9-206.x86_64.qcow2 : run : -mount /dev/sda1 / : cat /etc/redhat-release But 'guestfish' was interpreting the '-mount' command as an argument to 'guestfish' itself. The solution was to escape that string of commands with '--': $ guestfish -- add rhel-guest-image-6.9-206.x86_64.qcow2 : run : -mount /dev/sda1 / : cat /etc/redhat-release I scoured the man page[0] for mention of this usage and did not find anything suggesting this route. (Although some Google searches lead me to believe this is a way to signify the end of command options...) Even if this is not a 'guestfish' specific behavior, I think it would be useful to note this in the man page. [0] http://libguestfs.org/guestfish.1.html
Fixed with https://github.com/libguestfs/libguestfs/commit/693a8175ee1fb520967d576f00df2ff28b6425e0 which is in libguestfs >= 1.37.38.