Terminal (Bash) - Process Management and Conditional execution

Process Management

Run command in background

Imagine that you want to execute a command, but you want to keep using the prompt. To do that you need to execute the command like this:

$ command1 &
[1] 1234


The command1 will run in the background and the process id (PID) is 1234.

List processes

To list the processes running at your machine we can use the "ps" command.

$ ps
  PID TTY          TIME CMD
    8 tty1     00:00:00 bash
 1383 tty1     00:00:00 ps

Kill processes

To kill a process currently running we can use the "kill" command

$ kill 1234
[2]+ Terminated command1

The "kill" command sends signals to processes. And there is a variety of signals that the the "kill" command can send to processes.

Signal Number Name Description
1 SIGHUP Hang up signal
2 SIGINT Interrupt signal
9 SIGKILL Kill signal
15 SIGTERM Termination signal

Conditional Execution

Run command1 and if succeeds, then, run command2

command1 && command2

Run command2 if, and only if, command1 fails

command1 || command2
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