What is the process of exit status?
Get exit code of a background process
- Run the command CMD in parallel as a background process ( CMD & ).
- In the main script, have a loop to monitor the spawned command every few seconds.
- Exit the loop when the spawned command terminates.
- Capture and report the exit code of the spawned process.
What is the exit value returned by a process to the system in case of abnormal termination?
A non-zero value of status code is generally used to indicate abnormal termination. This is similar exit in C/C++. exit(0) : Generally used to indicate successful termination. exit(1) or exit(-1) or any other non-zero value – Generally indicates unsuccessful termination.
What does the exit status in Linux mean?
The exit status is an integer number. The Linux man pages stats the exit statuses of each command. 0 exit status means the command was successful without any errors. A non-zero (1-255 values) exit status means command was failure.
Is there an exit code when a process is killed?
Strictly speaking, there’s no exit code when a process is killed by a signal: what there is instead is an exit status. In a shell script, the exit status of a command is reported via the special variable $?. This variable encodes the exit status in an ambiguous way: If the process exited normally then $? is its exit status.
What is the exit code for a process in Unix?
On most unix variants, this value is taken modulo 256: everything but the low-order bits is ignored. The status of a child process is returned to its parent through a 16-bit integer in which bits 8–15 are the process’s exit code if the process exited normally, or 0 if the process was killed by a signal.
When to use value of exit status in shell script?
You can use value of exit status in the shell script to display an error message or take some sort of action. For example, if tar command is unsuccessful, it returns a code which tells the shell script to send an e-mail to sysadmin.