How to create a screen executing given command?

Question

i'm fairly new in *nix. Is there a way to create a screen, which will immediately execute a given command sequence (with their own arguments)? Two hours of googling yields nothing - perhaps because I can't clearly state the question.

I hope for something like

screen -dmS new_screen exec "cd /dir && java -version"

I am using screen v4.00.03 and CentOS 5.5 (kernel ver. 2.6.18-194.26.1.el5.028stab079.2)

See if this helps: http://stackoverflow.com/questions/543737/how-do-you-start-unix-screen-command-with-a-command — holygeek, Aug 13 '11 at 08:09
Thank you, that helps indeed. Would you post this as answer, so I can accept it? — Alex Abdugafarov, Aug 13 '11 at 09:08

kR105 · Answer 1 · 2021-09-24T16:42:12.980

You create a screen with a name and in detached mode:

screen -S "mylittlescreen" -d -m

Then you send the command to be executed on your screen:

screen -r "mylittlescreen" -X stuff $'ls\n'

The stuff command is to send keystrokes inside the screen. The $ before the string command is to make the shell parse the \n inside the quotes, and the newline is required to execute the command (like when you press enter).

This is working for me on this screen version:

$ screen -v

Screen version 4.00.03jw4 (FAU) 2-May-06

Please see man screen for details about the commands.

score 41 · Accepted Answer · answered Aug 13 '11 at 08:10

41

The problem is that using the 'exec' screen command does not start a shell. 'cd' is a shell builtin, so you need a shell for it. Also, you need a shell that remains running so that screen does not terminate.

You can use the -X option to screen to send commands to a running screen session, and the 'stuff' command to send keystrokes to the current window. Try this:

screen -dmS new_screen sh
screen -S new_screen -X stuff "cd /dir
"
screen -S new_screen -X stuff "java -version
"

Yes, you need to put the quotes on the next line in order for the commands to be executed.

answered Aug 13 '11 at 08:10

mloar

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1

Doesnt work, when I attach to a sceen, there is nothing executed – Alex Abdugafarov Aug 13 '11 at 09:09
1

Seems to work only if screen is attached before `screen -X stuff` is run. – highsciguy Nov 24 '12 at 22:00
11

I got this to work for me by including `-p 0` in there (`screen -S new_screen -p 0 -X stuff "..."`) – Destin Jan 09 '13 at 21:25
10

You can use `$'command \n'` instead of putting the the double quote on the next line. See [this](http://stackoverflow.com/a/3182519/693869) – Dave Butler Jun 24 '13 at 16:52
This wasn't working for me, please see my answer for what worked on my system. – kR105 Dec 13 '13 at 03:06
6

@mloar what is the purpose of `stuff` here? – DimG Sep 22 '16 at 20:47
you can use `^M` instead of literal newline in argument to stuff – loa_in_ Mar 25 '18 at 21:59
1

@DimG this is 2 years old so sorry but `stuff` emulates the typing of a command it "stuffs" the text input into the terminal, this is basically a hacky solution as screen does not natively support the desired behavior – Robbie Milejczak Oct 19 '18 at 15:29

Tushar Goswami · Answer 3 · 2016-12-02T10:33:12.160

8

screen -dmS screen_name bash -c 'sleep 100'

This will create new screen named screen_name. And inside the screen it will sleep for 100 seconds.

Note that if you type some command in place of sleep 100 which terminates immediately upon execution, the screen will terminate as well. So you wont be able to see the screen you just created

edited Dec 02 '16 at 10:33

answered Sep 21 '16 at 09:34

Tushar Goswami

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score 2 · Answer 4 · answered May 17 '14 at 22:11

I wanted to launch remote screens from within a bash script with some variables defined inside the bash script and available inside screen. So what worked for me was

#!/bin/bash
SOMEVAR1="test2"
# quit existing if there is one running already, be careful
screen -D -RR test1 -X quit || true
screen -dmS test1
screen -r test1 -p 0 -X stuff $"echo ${SOMEVAR1} ^M"

Where the return character, ^M, you need to enter using vim as

i CTRL-V ENTER ESCAPE

score 2 · Answer 5 · answered Jan 28 '17 at 08:40

2

Another approach

First line cd to the your directory. Second line start a new screen session named new_screen with bash. Third line executing java -version

cd /dir
screen -dmS new_screen bash
screen -S new_screen -p 0 -X exec java -version

answered Jan 28 '17 at 08:40

Dilushan

143
1
10

score 1 · Answer 6 · edited Jan 05 '16 at 15:35

1

I think that you can use this

function exec_in_screen() {
  name=$1
  command=$2
  screen -dmS $name sh; screen -S $name -X stuff "$command\n";
}

Then...

exec_in_screen "test" "ls"

edited Jan 05 '16 at 15:35

The_Black_Smurf

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answered Jan 05 '16 at 14:46

Pedro Rodrigues

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score -3 · Answer 7 · answered Aug 13 '11 at 08:10

-3

Yes, what you want is the "stuff" command

for example

screen -dmS new_screen -X stuff "cd /dir && java -version

"

the second quote is on the next line so that it executes when sent

answered Aug 13 '11 at 08:10

dukevin

22,384
36
82
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5

This results in "No screen session found." message – Alex Abdugafarov Aug 13 '11 at 09:02

How to create a screen executing given command?

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