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Deleting old files from directory

by Anonymous Monk
on Sep 27, 2011 at 19:13 UTC ( #928152=perlquestion: print w/ replies, xml ) Need Help??
Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks!
I need to get rid of text files in a directory if they are older than 10 days, I have coded this way:
... #del files if older than 10 days::: my @files = </myfiles/*.txt>; if (@files) { foreach my $delfiles (grep {-f && (10 < -M)} @files) { print "\n Deleting::: $delfiles\n"; unlink $delfiles; } } ...
Just need to know if this is efficient or if there is a better way of doing this.
Thanks for looking!

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Re: Deleting old files from directory
by TomDLux (Vicar) on Sep 27, 2011 at 19:39 UTC

    Does that even work? "perldoc -f -X" gives the example:

    while (<>) { chomp; next unless -f $_; # ignore specials #... }

    From which I gather the filetests don't take a default "$_". But once you've tested "-f $_", you can re-use the data structure from that query for the -M test by specifying a single underscore: "-M _". Personally I would do it as in the example, with a while, rather than loading all the filenames ... potentially a large number. I would also use a variable rather than "$_", because when you nest loops or call routines, the value of $_ might be altered.

    As Occam said: Entia non sunt multiplicanda praeter necessitatem.

      Um, grep always works with $_, and OP already has named variable $delfiles
      From which I gather the filetests don't take a default "$_".

      Well if you read "perldoc -f -X" you'll see it says:

          -X FILEHANDLE
          -X EXPR
          -X DIRHANDLE
          -X      A file test, where X is one of the letters listed below.  This unary
                  operator takes one argument, either a filename, a filehandle, or a
                  dirhandle, and tests the associated file to see if something is true
                  about it.  If the argument is omitted, tests $_, except for "-t", which
                  tests STDIN.  Unless otherwise documented, it returns 1 for true
                  and '' for false, or the undefined value if the file doesn't exist.  Despite
                  the funny names, precedence is the same as any other named unary operator.
      

Re: Deleting old files from directory
by Anonymous Monk on Sep 27, 2011 at 19:48 UTC

    Just need to know if this is efficient or if there is a better way of doing this.

    It is more efficient to stat only once, ie

    grep {-f $_ and 10 < -M _ }
    stat, -X
      this is what you mean?
      foreach (grep {-f $_ and 10 < -M _ } @files) { print "\n Deleting::: $_\n"; unlink $_; }

        Almost

        Simply replace EXISTING grep block with mine, no need to change anything else

Re: Deleting old files from directory
by chrestomanci (Priest) on Sep 27, 2011 at 20:03 UTC

    If you are using unix/linux, then an alternative way to find and delete old files is with find and xargs:

    find <directory> -type f -ctime +10 -name "*some*pattern*.txt" | xargs rm -f

    I have fragments like that in the crontab for the systems I maintain, as it is very easy to setup and then just leave to run for ever.

      or better using -delete from find actions (in this case -maxdepth is needed too)

      why ctime and not mtime ?

      In the other side, maybe using Find, could be more efficient? I don't know

      Regards,
      To handle spaces in filenames:
      find <directory> -type f -mtime +10 -name "*some*pattern*.txt" -exec r +m -f '{}' \;
      On first run(s), you should consider using ls -l instead of rm -f.

      I see you've used -ctime; here are the differences among Unix timestamps:

      • Access Time (atime) - time that the file was last accessed (e.g. read) or written to.
      • Modify Time (mtime) - time the actual contents of the file were last modified.
      • Change Time (ctime) - the time that the inode information (permissions, name, etc., i.e. the metadata) was last modified.

      Update: atime info corrected; for more see man 2 stat.

      Have a nice day, j

        I use an explicit pipe to xargs instead of using the built in delete action, because that way it is easier to check I am deleting the correct files, as I can use ls on the end of the xargs command instead of rm.

        Another way to handle spaces in filenames is to configure find to separate output with nulls instead of spaces, and then have xargs expect those nulls.

        find <directory> <conditions> -print0 | xargs -0 ls -l
      Notice also that systems like OS/X may require a slightly different syntax, as may Unix shells other than 'bash.'
Re: Deleting old files from directory
by Lotus1 (Chaplain) on Sep 27, 2011 at 20:41 UTC

    Here is how to do it without the array and without using grep.

    I prefer File::Glob these days since it allows whitespace in the path but it won't work like this in a while loop so I end up with a foreach loop and an array.

    #!/usr/bin/perl use warnings; use strict; while (<test/*.txt>) { if (-f && 10 < -M _) { print "\n Deleting::: $_\n"; unlink or warn "--Could not unlink $_: $!"; } }
Reaped: Re: Deleting old files from directory
by NodeReaper (Curate) on Sep 28, 2011 at 12:53 UTC

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