If you ever need to save the history of your Unix shell session, one of the easiest ways to do it is to use the script command, found in most Unix systems.

Simply provide the file name for your log as a command line parameter:

$ script /tmp/unix-session.log

After starting the command, you’ll be able to do whatever you want, and once you’re done you can use the standard Ctrl+D to end the session recording. The generated log file will have both the commands you have typed during your session and the output generated by these commands.

Your session log with also include the timestamps marking the start and the finish of your recording.

Here’s a sample session showing you how you use the script command:

$ script /tmp/unix-session.log
Script started, file is /tmp/unix-session.log
$ uname -a
Linux simplyunix.com 2.6.16.29-xen #3 SMP Sun Oct 15 13:15:34 BST 2006 x86_64 GNU/Linux
$ exit
Script done, file is /tmp/unix-session.log

Now, if we were to cat the log file generated in this example, we’d see the following:

$ cat /tmp/unix-session.log
Script started on Tue Nov 20 16:48:08 2007
$ uname -a
Linux simplyunix.com 2.6.16.29-xen #3 SMP Sun Oct 15 13:15:34 BST 2006 x86_64 GNU/Linux
$ exit

Script done on Tue Nov 20 16:48:12 2007

Have you got a better way to save your sessions? Let me know! (saving logs from gnome-terminal and Putty doesn’t count, mind you!)

I had a need to scan a huge directory tree today, identifying the users and Unix groups owning all the files. The problem I faced was too long usernames and group names which meant the

find /directory -ls

command which I normally use for such tasks wasn’t terribly useful because there was no space delimiter between a username and a group. Results of such scan of the directory tree will have to later be parsed by other tools, and that’s why proper splitting of the output into separate fields is so important.

This issue was motivational enough to refresh my Perl skills and sketch the following script (based entirely on this Never Run Unix Find Again article).

It’s a very simple piece of code which takes a directory to scan as a parameter.

How this works

As you can see, we’re using the standard File:Find functionality, and the two parameters find function takes are the wanted function, where you put conditions for your search.

Within this function, you call lstat to obtain all the necessary information about each directory entry, and then output the necessary fields.

Perl code

#!/usr/bin/perl
use File::Find;
if ($ARGV[0] ne "") {
        $dir = $ARGV[0];
} else {
        print "Please specify a directory!";
        exit;
}

find &wanted, $dir;

sub wanted {
  my $dev;         # the file system device number
  my $ino;         # inode number
  my $mode;        # mode of file
  my $nlink;       # counts number of links to file
  my $uid;         # the ID of the file's owner
  my $gid;         # the group ID of the file's owner
  my $rdev;        # the device identifier
  my $size;        # file size in bytes
  my $atime;       # last access time
  my $mtime;       # last modification time
  my $ctime;       # last change of the mode
  my $blksize;     # block size of file
  my $blocks;      # number of blocks in a file
  my $user;	# username
  my $group;	# unix group name

#Right below here your telling lstat to retrieve all this info on each and every file/directory. Each and every file/directory is written to $_.

  (($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks) = lstat($_));
  $user = getpwuid($uid);
  $group = getgrgid($gid);

  print $File::Find::name . ":$mode:$size:$user:$group:$ctime:$mtimen";
}

Hope you find this useful. Good luck with finding all your files! 🙂

For further reading, please consult the Perldoc section on File:Find.