Programming

At many places in program I see exit() being called with 2 passed as parameter to it.

Code:

exit(2);

What does this 2 stands for?
Can I get a list all such parameters to exit?

This is just a exit status code that script returns to what ever called it, most of the time it it is non-zero that means it is trying to tell the caller there was some type of error or exception condition that occurred.

Zero means success, anything else means some sort of error, but the exact meanings are specific to the program.

Some applications and UNIX code follow the sysexits protocol

For example see:
sysexits(3) - preferable exit codes for programs

Hello,

I want to know what is the meaning of code
exit(3);

You have to ask the person who wrote the code. Lots of things simply return what appears to us as an arbitrary non-zero number on error. The man page usually indicates what the return codes mean -- if this error came from a command that is documented on your system.

A direct answer: nobody, by themselves, can know for sure without a lot of research. Either reading the original code or asking the coder is the best way to know. Sometimes a manpage can help.

You could run

Code:

grep progname *

in any directory containing scripts that are written, where progname = the script that gives that exit. The program that called it will use the

Code:

$?

construct, if it is for a Bourne script, to decide what to do if the exit code = 3.