I’m writing a Python script to parse various logs across different hosts.
I can successfully run bash scripts via Python’s subprocess module, however, I want to minimize the number of ssh calls, so I’m trying to combine ssh, grep, and find into 1 command.
The problem begins when some hosts may not have any log files. My command is something like:
ssh SOME_HOST 'grep "SOME_VALUE" $(find SOME_PATH -type f -name "*.log")'
When there are no log files, this becomes grep "SOME_VALUE" and hangs forever. I tried wrapping it in double quotes so that it becomes grep "SOME_VALUE" "" instead:
ssh SOME_HOST 'grep "SOME_VALUE" "$(find SOME_PATH -type f -name "*.log")"'
Now I have the exact opposite problem: when there are some logs found, I get:
grep: FILE_A^JFILE_B^J... : No such file or directory
I’ve been stuck on this for a few days and googling / RTFMing hasn’t helped much. I have tried tr to replace newlines with spaces but got some other weird errors 🙁 Is there an easy way to do this in one command?
>Solution :
Add an extra filename argument so the argument list is never empty. You can use /dev/null as a dummy file that never matches grep.
ssh SOME_HOST 'grep "SOME_VALUE" $(find SOME_PATH -type f -name "*.log") /dev/null'