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B.26. Converting find Command Lines to Perl
A common task for a system administrator is to recursively search the
directory tree for certain items. On Unix, this is typically done
with the find command. We can do that directly from
Perl, too.
The find2perl command, which comes with Perl, takes
the same arguments that find does. Instead of
finding the requested items, however, the output of
find2perl is a Perl program that finds them. Since
it''s a program, you can edit it for your own needs. (The
program is written in a somewhat odd style.)
One useful argument that''s available in
find2perl but not in the standard
find is the
-eval option. This says that what follows
it is actual Perl code that should be run each time that a file is
found. When it''s run, the current directory will be the
directory in which some item is found, and $_ will
contain the item''s name.
Here''s an example of how you might use
find2perl. Suppose that you''re a system
administrator on a Unix machine, and you want to find and remove all
of the old files in the /tmp
directory.[422] Here''s the command that writes the
program to do that:
[422]This is a task typically done by a
cron job at some early-morning hour each
day.
$ find2perl /tmp -atime +14 -eval unlink >Perl-program
That command says to search in /tmp (and
recursively in subdirectories) for items whose atime (last access
time) is at least 14 days ago. For each item, the program should run
the Perl code unlink, which will use
$_ by default as the name of a file to remove. The
output (redirected to go into the file
Perl-program) is the program that does all of
this. Now you merely need to arrange for it to be run as needed.
