# How to debug shell commands **URL:** \ **Category:** Ansible Project\ **Created:** [April 24, 2012, 8:02pm UTC](https://forum.ansible.com/t/how-to-debug-shell-commands/11442 "2012-04-24T20:02:05Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Art\_Zemon](https://avatars.discourse-cdn.com/v4/letter/a/3da27b/32.png) [@Art\_Zemon](https://forum.ansible.com/u/Art_Zemon)\ **Post date:** [April 24, 2012, 8:02pm UTC](https://forum.ansible.com/t/how-to-debug-shell-commands/11442/1 "2012-04-24T20:02:05Z")
I tried a command with the shell and it just hung: > ansible -D -i server.lst [cloud1.hens-teeth.net](http://cloud1.hens-teeth.net) -m shell -a ‘/usr/bin/mysqlcheck -uadmin -p$(cat /etc/psa/.psa.shadow) --all-databases’ No output at all. More on that in a bit. It works fine with ssh: > ssh [cloud1.hens-teeth.net](http://cloud1.hens-teeth.net) ‘/usr/bin/mysqlcheck -uadmin -p$(cat /etc/psa/.psa.shadow) --all-databases’ Which led me to wondering about how to debug something like this. I had hoped that -D would give me something to work with but I got nada. Short of diving into the Python code and adding print statements, do you have suggestions? Returning to the command that I wanted to run, I think that it is waiting for a password to be entered. It I put some backslashed in front of the dollar sign, I get different output. I haven’t found a quantity of backslashed that work. How many do you think I should have? Thanks, – Art Z. ---
**Author:** ![Michael\_DeHaan](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@Michael\_DeHaan](https://forum.ansible.com/u/Michael_DeHaan)\ **Post date:** [April 24, 2012, 8:30pm UTC](https://forum.ansible.com/t/how-to-debug-shell-commands/11442/2 "2012-04-24T20:30:00Z")
> I tried a command with the shell and it just hung: > > > ansible -D -i server.lst [cloud1.hens-teeth.net](http://cloud1.hens-teeth.net) -m shell -a ‘/usr/bin/mysqlcheck -uadmin -p$(cat /etc/psa/.psa.shadow) --all-databases’ > > No output at all. More on that in a bit. > It works fine with ssh: > > > ssh [cloud1.hens-teeth.net](http://cloud1.hens-teeth.net) ‘/usr/bin/mysqlcheck -uadmin -p$(cat /etc/psa/.psa.shadow) --all-databases’ > > Which led me to wondering about how to debug something like this. I had hoped that -D would give me something to work with but I got nada. Short of diving into the Python code and adding print statements, do you have suggestions? -D provides module debug output only. > Returning to the command that I wanted to run, I think that it is waiting for a password to be entered. It I put some backslashed in front of the dollar sign, I get different output. I haven’t found a quantity of backslashed that work. How many do you think I should have? Ansible shouldn’t ask for a password unless you use --ask-pass. Note that ansible is trying root unless you pass in “-u” to ansible. This should of course immediately die, not hang. Sudo may hang if you were using --sudo, at least in 0.3 implementations. ---
**Author:** ![Art\_Zemon](https://avatars.discourse-cdn.com/v4/letter/a/3da27b/32.png) [@Art\_Zemon](https://forum.ansible.com/u/Art_Zemon)\ **Post date:** [April 24, 2012, 9:47pm UTC](https://forum.ansible.com/t/how-to-debug-shell-commands/11442/3 "2012-04-24T21:47:58Z")
Michael, ansible wasn’t waiting for a password. I think that mysqlcheck was waiting for a password. I think that > $(cat /etc/psa/.psa.shadow) evaluated to an empty string, which would make mysqlcheck prompt for a password. Is there a way to get > /usr/bin/mysqlcheck -uadmin -p$(cat /etc/psa/.psa.shadow) --all-databases to run properly in the shell module? I enclosed the whole thing in single quotes and tried 0, 1, 2, 4, 6 and 8 backslashes in front of the dollar sign. None worked. With ssh, it’s easy. Just type: > ssh [cloud1.hens-teeth.net](http://cloud1.hens-teeth.net) ‘/usr/bin/mysqlcheck -uadmin -p$(cat /etc/psa/.psa.shadow) --all-databases’ No backslashes needed at all. – Art Z. ---
**Author:** ![Michael\_DeHaan](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@Michael\_DeHaan](https://forum.ansible.com/u/Michael_DeHaan)\ **Post date:** [April 24, 2012, 10:02pm UTC](https://forum.ansible.com/t/how-to-debug-shell-commands/11442/4 "2012-04-24T22:02:57Z")
your local shell MAY be eating things. Try escaping the $? ---
**Author:** ![Seth\_Vidal](https://avatars.discourse-cdn.com/v4/letter/s/7ba0ec/32.png) [@Seth\_Vidal](https://forum.ansible.com/u/Seth_Vidal)\ **Post date:** [April 24, 2012, 10:05pm UTC](https://forum.ansible.com/t/how-to-debug-shell-commands/11442/5 "2012-04-24T22:05:34Z")
in lieu of $(stuff) try: `stuff` I've found backticks are easier to swallow by the shell. -sv ---
**Author:** ![Michael\_DeHaan](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@Michael\_DeHaan](https://forum.ansible.com/u/Michael_DeHaan)\ **Post date:** [April 24, 2012, 10:09pm UTC](https://forum.ansible.com/t/how-to-debug-shell-commands/11442/6 "2012-04-24T22:09:41Z")
Oh, you WANT the shell to evaluate that locally. Interesting. ---
**Author:** ![Art\_Zemon](https://avatars.discourse-cdn.com/v4/letter/a/3da27b/32.png) [@Art\_Zemon](https://forum.ansible.com/u/Art_Zemon)\ **Post date:** [April 25, 2012, 12:18pm UTC](https://forum.ansible.com/t/how-to-debug-shell-commands/11442/7 "2012-04-25T12:18:31Z")
Seth: I’ll try backticks and see if it works better. Michael: No, I want the command executed remotely, not locally. BTW, I do understand that I am moving afield from “configuration management” into “system management” and that this is not what ansible is intended to do. I was just playing with using ansible in lieu of pssh and hit this curiosity. – Art Z.