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perl, how to find out if a file exist

Posted on 2011-09-29
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Last Modified: 2012-05-12
In perl, how do I check if a file exist?
#if file exist, print message
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Question by:rgbcof
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10 Comments
 
LVL 10

Accepted Solution

by:
jeromee earned 200 total points
ID: 36815628
Check this out: http://perldoc.perl.org/functions/-X.html

my $myfile = "/tmp/test.txt";
if( -e $myfile ) {
    print "$myfile exists\n";
} else {
    print "$myfile does not exist\n";

}

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Author Comment

by:rgbcof
ID: 36815708
It works.  Thanks.
0
 
LVL 23

Assisted Solution

by:nemws1
nemws1 earned 50 total points
ID: 36815710
joremee is correct - you want the '-e' option.  The only change I'd make to his code is to put double-quotes around the file argument in line 2 (in case it has a space or other odd character):
if( -e "$myfile" ) {

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Author Closing Comment

by:rgbcof
ID: 36815994
It works.  Thanks
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LVL 10

Expert Comment

by:jeromee
ID: 36815996
Hi nemws1,
This script being a perl script, I don't believe that the double quotes are required.
Please correct me if I'm wrong.
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LVL 84

Expert Comment

by:ozo
ID: 36816974
the quotes are not required
0
 
LVL 10

Expert Comment

by:jeromee
ID: 36817162
Thanks Ozo.
I thought I was going crazy for a sec.
0
 
LVL 23

Expert Comment

by:nemws1
ID: 36817197
I should have been more clear - my apologies, jeromee.  No, quotes are not required for a single scalar argument.  The problem is that people get in the habit of doing it this way and then they write something like this:
 
$p="/home/user"
$f="datafile"
if (-e $p/$f) {
   .....
}

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Which is obviously incorrect.  IMO, it is good coding habit (and also helps with readability) to put double quotes around files/paths.  Saves you many a headache.
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LVL 84

Expert Comment

by:ozo
ID: 36817265
on the other hand, if people get in the habit of using unnecessary quotes
they may write something like this:

open $myfile,"/tmp/test.txt" or die;
if( -e "$myfile" )

which is not so obviously incorrect.
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LVL 10

Expert Comment

by:jeromee
ID: 36817298
No apologies req'd nemws1.
Thanks anyway.
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