Output redirection with “screen” command
-
13-11-2019 - |
Question
Might be a simple problem, but I am running CentOS 5.4 command line remotely. I want to redirect the output of a simple Java file, lets say loop to print a hundred thousand numbers in console to a text file. The thing is, I have to use the 'screen' command to be able to run it in background even if I loose my session with the remote computer and this command does not write to the desired file.
I tried the method screen java MyClass >& log.txt
also screen java MyClass > log.txt
but it does not write to the file. Why is this happening and is there any solution?
Solution
You can do this with the nohup
command. Here's an example.
$ cat Foo.java
public class Foo {
public static void main(String[] args) throws InterruptedException
{
for(int i = 0 ; i < 1000 ; i++)
{
System.out.println(i);
Thread.sleep(1000);
}
}
}
$ javac Foo.java
$ nohup java Foo > foo.txt &
[3] 29542
$ cat foo.txt
0
1
2
3
4
5
$ exit
<< relaunch shell >>
$ cat foo.txt
0
1
...
29
30
The reason this doesn't work with screen
is because screen
doesn't interpret your arguments like the shell does. If you were to do this with screen
, it would have worked:
screen /bin/bash -c 'java Foo > foo.txt'
OTHER TIPS
sample_script.sh
#!/bin/bash
#start screen in detached mode with session name 'default_session'
screen -dmS "default_session"
#redirect output to abc.log
screen -S default_session -X stuff "script -f /tmp/abc.log\n"
#execute your command
screen -S default_session -X stuff "your command goes here...\n"