What is the meaning of exit 1 in shell script?

What is the meaning of exit 1 in shell script?

Exit codes are a number between 0 and 255, which is returned by any Unix command when it returns control to its parent process. Other numbers can be used, but these are treated modulo 256, so exit -10 is equivalent to exit 246 , and exit 257 is equivalent to exit 1 .

What does negative exit code mean?

If the exit code is a negative number, the resulting exit status is that number subtracted from 256. So, if your exit code is 20, then the exit status is 236. The solution, to me, is to avoid using exit codes that are reserved and out-of-range. The proper range is 0-255.

How do you check the exit code?

To check the exit code we can simply print the $? special variable in bash. This variable will print the exit code of the last run command.

What is the exit status of a command?

The exit status of an executed command is the value returned by the waitpid system call or equivalent function. Exit statuses fall between 0 and 255, though, as explained below, the shell may use values above 125 specially. Exit statuses from shell builtins and compound commands are also limited to this range.

Where is the exit status of a command stored?

Explanation: The exit status of a command is that particular value which is returned by the command to its parent. This value is stored in $?.

Why do we use exit 0?

The function exit(0) is a jump statement of C++. It is used to terminate the program or let the control exit out of the program. It reports the operating system about the successful termination of the program which indicates to the operating system that the task of the program has been successfully completed.

What does exit status 0 mean?

With bash commands the return code 0 usually means that everything executed successfully without errors. exit also makes your script stop execution at that point and return to the command line.

What is the exit status of a list in Ksh?

If the value of the arithmetic expression is non-zero, the exit status is 0, otherwise the exit status is 1. Execute list in a separate environment. Note, that if two adjacent open parentheses are needed for nesting, a space must be inserted to avoid evaluation as an arithmetic command as described above.

Where does the command name go in Ksh-Unix?

The command name is passed as argument 0 (see exec (2)). The value of a simple-command is its exit status; 0-255 if it terminates normally; 256+ signum if it terminates abnormally (the name of the signal corresponding to the exit status can be obtained via the -l option of the kill built-in utility).

When does the if command return a zero exit status?

If the if list has non-zero exit status and there is no else list, then the if command returns a zero exit status. A while command repeatedly executes the while list and, if the exit status of the last command in the list is zero, executes the do list; otherwise the loop terminates.

How are functions defined in ksh and Bash?

Ksh and bash optional syntax for defining a function. These functions may define local variables and local signal traps and so can more easily avoid side effects and be reused by multiple scripts. A function may read or modify any shell variable that exists in the calling script. Such variables are global .