Error "no shell available"

For importing data into Filemaker with xml I’m creating and deleting files. The deletion of the files has a fallback solution of deleting with the shell (a simple rm). Now I’ve got an error message from a user “no shell available”. What does this mean? Google wasn’t able to help me out.

maybe the number of shells is limited?

e.g. like the file handles?

or its a restricted user account that cant use a shell in any way

@Normal: no, that was the first thing I asked. The error happens right in the middle of handling data. I’ll let the user check if Christians idea could be correct.

Stupid autocorrect

No idea about OS X really, but maybe this relates:

“The maximum number of processes available to a single user”

@Normal: nope, thick fingers. I got used to it.