From BASH to Perl

[David R. Waddell]

I think find2perl is a hack for windoz os'es. As Keary indicates
there are better ways on a Unix box.

At 12:03 PM 1/4/02 -0700, Keary Suska wrote:
>It is not necessary to emulate Unix commands in your Perl script unless you
>are specifically trying to avoid launching a subshell. One of many simple
>ways to do what you want in perl:
>
># $directory would be acquired from command line or whatever
>$command = "find $directory -type f -ls -xdev -fstype ext2 \( -iname
>'*personal*' -o -iname '.*personal*' \) -print"
>
># open pipe from system command
>open FIND, "$command |" or die $!
>while( <FIND> ) {
>  # $_ will have each file name found with full path name
>  # do what you want with it here
>}
>close FIND;
>
>That's it. There are security and robustness considerations (checking path,
>untainting input, checking SIGPIPE), but this is essentially all that is
>needed.
>
>Keary Suska
>Esoteritech, Inc.
>"Leveraging Open Source for a better Internet"
>
>> From: SoloCDM <deedsmis at aculink.net>
>> Reply-To: <deedsmis at aculink.net>, <pikes-peak-pm-list at happyfunball.pm.org>
>> Date: Fri, 4 Jan 2002 04:56:27 -0700
>> To: Pikes Peak Perl Mongers (Majordomo)
>> <pikes-peak-pm-list at happyfunball.pm.org>
>> Subject: From BASH to Perl
>> 
>> I am completely new to Perl, but not this list.  I have a BASH script
>> that I want to translate to Perl, so I started with the find command.
>> 
>> I found a find2perl perl script, which created the following script
>> from, "find2perl [directory] -type f -xdev -fstype ext2 \( -name
>> '*personal*' -o -name '.*personal*' \) -print":
>> 
>> ===================== Begin =====================
>> #! /usr/bin/perl -w
>> eval 'exec /usr/bin/perl -S $0 ${1+"$@"}'
>> if 0; #$running_under_some_shell
>> 
>> use strict;
>> use File::Find ();
>> 
>> # Set the variable $File::Find::dont_use_nlink if you're using AFS,
>> # since AFS cheats.
>> 
>> # for the convenience of &wanted calls, including -eval statements:
>> use vars qw/*name *dir *prune/;
>> *name = *File::Find::name;
>> *dir = *File::Find::dir;
>> *prune = *File::Find::prune;
>> 
>> 
>> # Traverse desired filesystems
>> File::Find::find({wanted => \&wanted}, '[directory]');
>> exit;
>> 
>> sub wanted {
>> my ($dev,$ino,$mode,$nlink,$uid,$gid);
>> 
>> (($dev,$ino,$mode,$nlink,$uid,$gid) = lstat($_)) &&
>> -f _ &&
>> !($File::Find::prune |= ($dev != $File::Find::topdev)) &&
>> ($dev >= 0) &&
>> (
>> /^.*personal.*\z/s
>> ||
>> /^\..*personal.*\z/s
>> ) &&
>> print("$name\n");
>> }
>> ===================== End =====================
>> 
>> I was startled to find more than was necessary and some extra
>> commands that I hadn't counted on (sub wanted { list }, use,
>> eval, if).  I understand the reason for the eval and if statements,
>> but again I know little of them.  I hadn't realized, until now,
>> that it was necessary to have the use commands.  Nevertheless,
>> when I executed the script, nothing was produced by the script.
>> 
>> The actual BASH find command was, "find [directory] -type f -ls
>> -xdev -fstype ext2 \( -iname '*personal*' -o -iname '.*personal*'
>> \) -print", which is piped into a while command in BASH with quotes
>> around the filenames, because there are spaces in the filenames
>> (filenames actually represented by variables in the BASH script).
>> 
>> One of my main concerns is manipulating a file and its data with
>> the find and loop commands to the end of each file.
>> 
>> I did find, in Perl In A Nutshell by O'Reilly, where the following
>> can manipulate the file:
>> 
>> while (<INFILE>) {
>> print OUTFILE, "$_\n";
>> }
>> 
>> I believe I understand $_ is the name as the input files data with
>> a return on the end.
>> 
>> -- 
>> Note: When you reply to this message, please include the mailing
>> list/newsgroup address and my email address in To:.
>> 
>> *********************************************************************
>> Signed,
>> SoloCDM
>> 
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