Python subprocess not executing properly

Question

I am having problems outputting a command to a running screen.

Using the following code:

import subprocess
subprocess.call(["screen", "-S jcmp", "-X stuff", "'kick Jman100'`echo -ne '\015'`"])

returns the following:

Use: screen [-opts] [cmd [args]]
 or: screen -r [host.tty]

Options:
-a            Force all capabilities into each window's termcap.
-A -[r|R]     Adapt all windows to the new display width & height.
-c file       Read configuration file instead of '.screenrc'.
-d (-r)       Detach the elsewhere running screen (and reattach here).
-dmS name     Start as daemon: Screen session in detached mode.
-D (-r)       Detach and logout remote (and reattach here).
-D -RR        Do whatever is needed to get a screen session.
-e xy         Change command characters.
-f            Flow control on, -fn = off, -fa = auto.
-h lines      Set the size of the scrollback history buffer.
-i            Interrupt output sooner when flow control is on.
-l            Login mode on (update /var/run/utmp), -ln = off.
-list         or -ls. Do nothing, just list our SockDir.
-L            Turn on output logging.
-m            ignore $STY variable, do create a new screen session.
-O            Choose optimal output rather than exact vt100 emulation.
-p window     Preselect the named window if it exists.
-q            Quiet startup. Exits with non-zero return code if unsuccessful.
-r            Reattach to a detached screen process.
-R            Reattach if possible, otherwise start a new session.
-s shell      Shell to execute rather than $SHELL.
-S sockname   Name this session <pid>.sockname instead of <pid>.<tty>.<host>.
-t title      Set title. (window's name).
-T term       Use term as $TERM for windows, rather than "screen".
-U            Tell screen to use UTF-8 encoding.
-v            Print "Screen version 4.00.03jw4 (FAU) 2-May-06".
-wipe         Do nothing, just clean up SockDir.
-x            Attach to a not detached screen. (Multi display mode).
-X            Execute <cmd> as a screen command in the specified session.

Error: Unknown option S jcmp
1
>>> subprocess.call(["screen", "-s jcmp", "-X stuff", "'command here'`echo -ne '\015'`"])
Use: screen [-opts] [cmd [args]]
 or: screen -r [host.tty]

Options:
-a            Force all capabilities into each window's termcap.
-A -[r|R]     Adapt all windows to the new display width & height.
-c file       Read configuration file instead of '.screenrc'.
-d (-r)       Detach the elsewhere running screen (and reattach here).
-dmS name     Start as daemon: Screen session in detached mode.
-D (-r)       Detach and logout remote (and reattach here).
-D -RR        Do whatever is needed to get a screen session.
-e xy         Change command characters.
-f            Flow control on, -fn = off, -fa = auto.
-h lines      Set the size of the scrollback history buffer.
-i            Interrupt output sooner when flow control is on.
-l            Login mode on (update /var/run/utmp), -ln = off.
-list         or -ls. Do nothing, just list our SockDir.
-L            Turn on output logging.
-m            ignore $STY variable, do create a new screen session.
-O            Choose optimal output rather than exact vt100 emulation.
-p window     Preselect the named window if it exists.
-q            Quiet startup. Exits with non-zero return code if unsuccessful.
-r            Reattach to a detached screen process.
-R            Reattach if possible, otherwise start a new session.
-s shell      Shell to execute rather than $SHELL.
-S sockname   Name this session <pid>.sockname instead of <pid>.<tty>.<host>.
-t title      Set title. (window's name).
-T term       Use term as $TERM for windows, rather than "screen".
-U            Tell screen to use UTF-8 encoding.
-v            Print "Screen version 4.00.03jw4 (FAU) 2-May-06".
-wipe         Do nothing, just clean up SockDir.
-x            Attach to a not detached screen. (Multi display mode).
-X            Execute <cmd> as a screen command in the specified session.

Error: Unknown option S jcmp

"jcmp" is the name of the screen session that was previously launched using an os.system() call

The answer by kindall is correct. But if you trust the command, then (& then only) You can use Shell=True option, in which case, you can provide the command as single string "...", instead of list [..., ...]. Similarly, you can have list as ["bash", "-c", "your entire command with args"]. — anishsane
– anishsane, Commented Jun 30, 2014 at 6:36
And if you don't want to use the shell, you can still use a single string and use shlex.split to break it up as the shell would, then pass that to subprocess.call. — kindall
– kindall, Commented Mar 17, 2015 at 16:56

kindall · Accepted Answer · 2014-06-30 03:03:40Z

14

You're getting that message because you are not passing the arguments correctly. Each argument should be an individual string in the list. That is, -S jcmp should not be a single argument but two; same for -X stuff.

subprocess.call(["screen", "-S",  "jcmp", "-X", "stuff", "'kick Jman100'`echo -ne '\015'`"])

answered Jun 30, 2014 at 3:03

kindall

185k36 gold badges291 silver badges321 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

devwanderer Over a year ago

I have a similar problem although I do exactly as you say: aws_command = ["aws","sqs","receive-message","--queue-url",queue_url,"--message_attribute_names", "data"] it prints out the error as "-message_attribte_names" and "data" are unknown arguments. But they do output the result correctly when typed directly into terminal –

Collectives™ on Stack Overflow

Python subprocess not executing properly

1 Answer 1

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related