CODEWITHSUNDEEP
pythonshellunixgrep
Aashish sharma Sharma
Aashish sharma Sharma

Reputation: 307

grep command from python

I used grep command from shell and it gave the result I wanted but when I run from my python script using os.popen it said

grep: SUMMARY:: No such file or directory

Normal grep command:

grep -A 12 -i "LOGBOOK SUMMARY:" my_folder/logbook.log

Python script

command="grep -A 12 -i LOGBOOK SUMMARY: my_folder/logbook.log"
result=os.popen(command)

Normal grep command gave the result I wanted. 2nd one said no such file or directory

Upvotes: 2

Views: 3359

Answers (1)

janos
janos

Reputation: 124704

You need to enclose the search pattern within quotes:

command="grep -A 12 -i 'LOGBOOK SUMMARY:' my_folder/logbook.log"

How to diagnose such problems? Start from the error message:

grep: SUMMARY:: No such file or directory

This error message tells that grep could not find a file named SUMMARY:.

The right question to ask is, why is grep looking for a file named SUMMARY:? And the answer is that on the command line you executed, somehow SUMMARY: is considered a filename:

command="grep -A 12 -i LOGBOOK SUMMARY: my_folder/logbook.log"

Of course! That's what would happen if you executed that command in the shell:

grep -A 12 -i LOGBOOK SUMMARY: my_folder/logbook.log

Here, the shell will split the command line on spaces, and pass to grep 3 arguments, LOGBOOK, SUMMARY: and my_folder/logbook.log. The first argument, LOGBOOK is used as the pattern to search for, and all remaining arguments are taken as filenames to search in.

Upvotes: 4

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