reading from directory

splitOnce has asked for the wisdom of the Perl Monks concerning the following question:

Hello Monks, I am trying to open a directory that contains lots of files , then I want to grep some information from each file and redrict the output to another file :

-MainDir
   - dflk.cpp
   - dll.cpp
   - cll.cpp
..
..
..
[download]

I am familiar with open when dealing with a file but how do you do this with directory :

opendir MainDir or die "";
while <>
`grep "theInfolookingfor" fileUnderDir > fileUnderDir.out`
cloes dir;
[download]

thanks

Comment on reading from directory Select or Download Code

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Re: reading from directory by CubicSpline (Friar) on Aug 19, 2002 at 23:12 UTC
You're right on track here. The way I usually do this is as follows: `opendir DIR, "MainDir" or die ""; while( $file = readdir(DIR) ) { #do whatever you want to the file } closedir DIR;` [download] One thing to note, this method includes directory names. If you just want to grep for a string in all .cpp files in the current directory, try using globs (this is still magic to me, btw) like so: `while( $file = <*.cpp> ) { #do something to the file }` [download] ~CubicSpline "No one tosses a Dwarf!"	[reply] [d/l] [select]
Re: Re: reading from directory by moodster (Hermit) on Aug 20, 2002 at 08:32 UTC
Since there is More Than One Way To Do It, you could also go for the object-oriented approach using DirHandle: `use DirHandle; my $dh = new DirHandle; $dh->open( 'MainDir' ); foreach ( grep /\.cpp$/, $dh->read ) { # do stuff } $dh->close;` [download] The DirHandle module is a wrapper around opendir and its relatives, so this is essentially the same as CubicSplines answer, just another way of writing it. Cheers, --Moodster	[reply] [d/l]
Re: reading from directory by Arien (Pilgrim) on Aug 19, 2002 at 23:56 UTC
If all you want to do is grep some files, why not actually use `grep(1)` to do that? — Arien	[reply] [d/l]
Re: Re: reading from directory by splitOnce (Acolyte) on Aug 20, 2002 at 14:00 UTC
thanks all :)	[reply]
Re: reading from directory by bart (Canon) on Aug 20, 2002 at 14:24 UTC
IMO you should be using File::Find. That will traverse a whole tree for you. `use File::Find; find sub { if(-f) { system("grep 'theInfoLookingFor' $_ >$_.out"); } }, $rootdir;` [download]	[reply] [d/l]