Detailed instructions for FG, BG, Jobs, &, Nohup, CTRL + Z commands in Linux

FG, BG, Jobs, &, Nohup, CTRL + Z command one, &

Add to the end of a command, you can put this command in the background execution, such as Gftp &

Two, CTRL + Z

You can put a command that is being executed in the foreground in the background and is paused, not executable

Third, Jobs

See how many commands are currently running in the background

• The JOBS-L option shows that the pid,jobs status of all tasks can be running, stopped, Terminated, but if the task is terminated (kill), the shell removes the process identity of the task from the list known to the current shell environment; , the Jobs command displays the task information that is running in the background or suspended in the current shell environment;

Iv. FG

Move commands in the background to the foreground to continue running

• If there are multiple commands in the background, you can use FG%jobnumber to bring up the selected command,%jobnumber is the ordinal (not PID) of the command being executed in the background through the jobs command.

V. BG

A command paused in the background to continue execution (performed in the background)

1. If there are multiple commands in the background, you can use BG%jobnumber to bring up the selected command,%jobnumber is the ordinal (not PID) of the command being executed in the background through the jobs command.

2. Move the task to the background run: Ctrl + Z, then BG, so that the process is moved to the background and the terminal can continue to accept commands.

3. Concept: Current task
   If there are 2 task numbers in the background, [1],[2]; If the first background task executes successfully and the second background task is still in progress, the current task will automatically become a background task for the background task number "[2]". So it can be concluded that the current task is subject to change. When the user enters commands such as FG, BG, and stop, the current task is changed if no quotation marks are added

Liu, Nohup

If you are running a process and you feel that the process will not end when you exit the account, you can use the Nohup command. This command can continue to run the process after you exit the account/close the terminal.

VII. termination of the process

1. Termination of the background process:

• Method One:
  View the job number (assuming num) through the jobs command, and then execute the kill%num
• Method Two:
  Use the PS command to view the job's process number (PID, assuming PID), and then execute the kill PID

1. Termination of the foreground process: Ctrl + C

• Other effects of Kill: Kill can terminate the process, but also send other signals to the process, using kill-l can see the signal of kill support.
• Sigterm is the signal that kill sends without parameters, meaning that the process terminates, but execution depends on whether the process supports it. If the process has not been terminated, you can use the Kill-sigkill PID, which is the kernel to terminate the process and the process cannot listen for this signal.

Process hangs (paused meaning bar)

1. Hang of background process:
   • Execute through the Stop command in Solaris, view the job number (assuming num) through the jobs command, and then execute the Stop%num;
   • In Redhat, the Stop command does not exist, and the process can be suspended by executing the command kill-stop PID;
   • When you want to re-execute the currently suspended task, the status of the suspended job can be changed from stopped to running through BG%num, and the command FG%num can be executed when it needs to be executed in the foreground instead;
2. Foreground process hangs: Ctrl + Z

• Use jobs to view tasks;
• Use FG%n to close.

Detailed instructions for FG, BG, Jobs, &, Nohup, CTRL + Z commands in Linux