Shell Programming and Scripting

Hi all,

I have came across the following line in a script and was not able to interpret the meaning despite searching in the web for answer, my guess is that it seems like a comment to me stating if 0 then return else exit

============================
: 0 - 999 [ 0 return, >0 exit ]
....
.....
============================

This line appear at the beginning of the script, can some experts enlighten me on this.

It would help to know which shell you are running?

In many shells ":" is a command equivalent to the unix command "true". The command does not actually give a syntax error but I can't see it doing anything useful as posted - bearing in mind that space characters are critical when posting shell script.
The various "====" and "...." etc. you post are syntax errors which makes me wonder what file this all came from. Maybe it is an error messages data file or something?

Hi,

It is running on a Korn Shell. The actual scripting is as follows:

#This is a common script used by other scripts
: 0 - 999 [ 0 return, >0 exit ]

error_msg()
{
echo "this is an error msg"
}

: nop command, return always exit status 0. You can give arguments if you like, end of line do nothing. End of line is parsed like any other command line.
: rm *
: $(date)
: or write some comments even # is better or "normal"
When true and false wasn't builtin command, in older script you can see ex.
while : ; do ...
: is always true