[SOLVED] How to run 'sed' using Python's Subprocess?

ozsnake · 08-01-2019, 12:48 PM

I'm trying to append some data after a matching pattern with sed. In bash it works fines. When i tried to run the same command in a python script, nothing is being appended.

The file's content:

Code:

# directive as shown below:
This is a configuration file.

In bash when i run sed, it works fine:

Code:

[root@centos ~]# sed -i '/^# directive* /a cfg_dir=\/etc\/nagios\/commands' count

[root@centos ~]# cat count
# directive as shown below:
cfg_dir=/etc/nagios/commands
This is a configuration file.

The python code:

Code:

test = ['command', 'local', 'test']

os.chdir('/root')

for t in test:
    sp.run(f"sed -i '/^# directive shown below* /a cfg_dir=\/etc\/nagios\/testing' count", shell=True)

Nothing's changed:

Code:

[root@centos ~]# python3 test.py

[root@centos ~]# cat count
# directive as shown below:
This is a configuration file.

I just don't get it.

ozsnake · 08-01-2019, 02:14 PM

Misspelled Error.

The solution:

for t in test:
sp.run(f"sed -i '/^# directive* /a cfg_dir=\/etc\/nagios\/{t}' count", shell=True)

individual · 08-01-2019, 08:03 PM

Is there any reason you couldn't write that sed statement in Python? It would be more efficient that having to create a subprocess just for for that.

ozsnake · 08-04-2019, 12:33 PM

Yeah you're right. A simple os.system would've been enough.