Command-Line – How to Use -exec Option in Find Command

simply add a -printf option before

find -printf '%p' -exec command \;

In wrapper script

exec is used mainly in wrapper scripts.

If you want to modify the environment for a program before executing the main program, you'd often write an script and at the end of it start the main program. But there is no need for the script to stay in memory at that time. So, exec is used in these cases so that, the main program can replace the mother script.

Here is a practical example of it. It's mate-terminal.wrapper script comes with mate-terminal. It starts the mate-terminal with some extra arguments by checking user's environments.

#!/usr/bin/perl -w

my $login=0;

while ($opt = shift(@ARGV))
{
    if ($opt eq '-display')
    {
        $ENV{'DISPLAY'} = shift(@ARGV);
    }
    elsif ($opt eq '-name')
    {
        $arg = shift(@ARGV);
        push(@args, "--window-with-profile=$arg");
    }
    elsif ($opt eq '-n')
    {
        # Accept but ignore
        print STDERR "$0: to set an icon, please use -name <profile> and set a profile icon\n"
    }
    elsif ($opt eq '-T' || $opt eq '-title')
    {
        push(@args, '-t', shift(@ARGV));
    }
    elsif ($opt eq '-ls')
    {
        $login = 1;
    }
    elsif ($opt eq '+ls')
    {
        $login = 0;
    }
    elsif ($opt eq '-geometry')
    {
        $arg = shift(@ARGV);
        push(@args, "--geometry=$arg");
    }
    elsif ($opt eq '-fn')
    {
        $arg = shift(@ARGV);
        push(@args, "--font=$arg");
    }
    elsif ($opt eq '-fg')
    {
        $arg = shift(@ARGV);
        push(@args, "--foreground=$arg");
    }
    elsif ($opt eq '-bg')
    {
        $arg = shift(@ARGV);
        push(@args, "--background=$arg");
    }
    elsif ($opt eq '-tn')
    {
       $arg = shift(@ARGV);
       push(@args, "--termname=$arg");
    }
    elsif ($opt eq '-e')
    {
        $arg = shift(@ARGV);
        if (@ARGV)
        {
            push(@args, '-x', $arg, @ARGV);
            last;
        }
        else
        {
            push(@args, '-e', $arg);
        }
        last;
    }
    elsif ($opt eq '-h' || $opt eq '--help')
    {
        push(@args, '--help');
    }
}
if ($login == 1)
{
    @args = ('--login', @args);
}
exec('mate-terminal',@args);

The point to notice here is, there is an exec call, which replaces this script in memory.

Here is a similar question answered in Unix & Linux StackExchange Site - https://unix.stackexchange.com/q/270929/19288

To redirect file-descriptors

Another common use of exec is in redirecting file-descriptors. stdin, stdout, stderr can be redirected to files using exec.

1. Redirecting stdout - exec 1>file will cause the standard output to be a file named file for the end of the current shell session. Anything to output to the display will be in the file.

2. Redirecting stdin - It can also be used to redirect the stdin to a file. For example, If you want to execute a script file script.sh, you can just redirect the stdin to the file using exec 0<script.sh.