Menu
I'm rushing against the clock for a programming assignment in which I have to run a number of instances of the same program on the same machine at the same time. Currently, I'm starting the instances one at a time, pressing Ctrl+z to pause them, and then doing 'bg %#' to resume execution in the background.
This is extremely tedious and time consuming to do every time I need to test a small change in my application, so I want to write a bash script that will start the multiple instances for me, however I don't know how to do the background switching in a script.
Can anybody please tell me how I can write a simple script that will start a long standing command, pause it, and resume it in the background?
Thanks
301
ctrl+z stops the process and returns you to the current shell. You can now type fg to continue process, or type bg to continue the process in the background. Research "bash job control" and see bash manual Job Control Basics.
$1 means an input argument and -z means non-defined or empty. You're testing whether an input argument to the script was defined when running the script.
In both cases, the -z flag is a parameter to the bash's "test" built-in (a built-in is a command that is built-into the shell, it is not an external command). The -z flag causes test to check whether a string is empty. Returns true if the string is empty, false if it contains something.
$() Command Substitution According to the official GNU Bash Reference manual: “Command substitution allows the output of a command to replace the command itself.
Do you want to just start it in the background? For example:
mycommand &
If you want finer grained job control, you can emulate Ctrl-Z and bg. Control-Z sends SIGTSTP ("tty stop") to the program, which suspends it:
kill -TSTP [processid]
And the bg command just sends it a SIGCONT:
kill -CONT [processid]
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
