Perl file test operator help
This is a really basic issue, but I'm new to perl and cannot work out what the issue is. I'm just trying to isolate the files in a directory, but the -d operator keeps treating all the folder contents as files ...
@contents is my array, and when I run this:
use strict;
if ($ARGV[1]) {
die("Error: You can only monitor one directory at a time\n");
}
my $directory = $ARGV[0] || die "Error: No directory defined\n";
opendir(DIR, $directory) || die "Error: Can't open dir $directory: $!";
my @contents = readdir(DIR);
foreach my $item(@contents) {
if (-d $item) { next; }
print"$item is a file\n";
}
closedir (DIR);
I keep getting both folders and files. Alternatively, if I use -f, I get nothing.
开发者_运维百科edit: this is the output -
file01.txt is a file
folder 01 is a file
folder 02 is a file
Screen shot 2010-04-18 at 1.26.17 PM.png is a file
I'm running this on OSX
edit:dir ls -l
output:
aaron ~/Documents/test: ls -l
total 112
-rw-r--r--@ 1 aaron staff 51235 18 Apr 13:26 Screen shot 2010-04-18 at 1.26.17 PM.png
-rw-r--r--@ 1 aaron staff 7 18 Apr 13:26 file01.txt
drwxr-xr-x 3 aaron staff 102 18 Apr 13:25 folder 01
drwxr-xr-x 2 aaron staff 68 18 Apr 13:25 folder 02
Solution
I was testing with '.' as the directory...you're testing with some other directory. The names read from the directory are then checked relative to the current directory. If I use some other directory name, I'll get almost everything except '.' and '..' listed as files, regardless.
If you prefix the name with the value of $ARGV[0], you'll get the expected result:
#!/bin/perl -w
use strict;
if ($ARGV[1]) {
die("Error: You can only monitor one directory at a time\n");
}
my $directory = $ARGV[0] || die "Error: No directory defined\n";
opendir(DIR, $directory) || die "Error: Can't open dir $directory: $!";
my @contents = readdir(DIR);
foreach my $item(@contents) {
next if -d "$ARGV[0]/$item";
print "$ARGV[0]/$item is a file\n";
}
closedir (DIR);
Previous attempts to explain
This works on MacOS X:
#!/bin/perl -w
use strict;
my @contents = <*>;
foreach my $item (@contents)
{
print "== $item\n";
next if -d $item;
print "$item is a file\n";
}
Test:
MiniMac JL: perl -c xx.pl
xx.pl syntax OK
MiniMac JL: perl xx.pl
== cproto-4.7g
== fpqsort1
fpqsort1 is a file
== fpqsort1.h
fpqsort1.h is a file
== fpqsort2
fpqsort2 is a file
== fpqsort2.c
fpqsort2.c is a file
== gcc-predef.h
gcc-predef.h is a file
== git-1.6.5.7
== go
== makefile
makefile is a file
== qs-test1.c
qs-test1.c is a file
== qs-test2.c
qs-test2.c is a file
== RCS
== rep-report.txt
rep-report.txt is a file
== select.c
select.c is a file
== soq
== xx.pl
xx.pl is a file
MiniMac JL:
Given a marginally modified version of the code in the question:
#!/bin/perl -w
use strict;
if ($ARGV[1]) {
die("Error: You can only monitor one directory at a time\n");
}
my $directory = $ARGV[0] || die "Error: No directory defined\n";
opendir(DIR, $directory) || die "Error: Can't open dir $directory: $!";
my @contents = readdir(DIR);
foreach my $item(@contents) {
print "<<$item>>\n";
next if -d $item;
print"$item is a file\n";
}
closedir (DIR);
Running it on the same directory as before, I get the output:
Minimac JL: perl yy.pl .
<<.>>
<<..>>
<<cproto-4.7g>>
<<fpqsort1>>
fpqsort1 is a file
<<fpqsort1.h>>
fpqsort1.h is a file
<<fpqsort2>>
fpqsort2 is a file
<<fpqsort2.c>>
fpqsort2.c is a file
<<gcc-predef.h>>
gcc-predef.h is a file
<<git-1.6.5.7>>
<<go>>
<<makefile>>
makefile is a file
<<qs-test1.c>>
qs-test1.c is a file
<<qs-test2.c>>
qs-test2.c is a file
<<RCS>>
<<rep-report.txt>>
rep-report.txt is a file
<<select.c>>
select.c is a file
<<soq>>
<<xx.pl>>
xx.pl is a file
<<yy.pl>>
yy.pl is a file
Minimac JL:
Note the Perlish idiom 'next if -d $item;
'. Also note the debugging techniques: print the names as they go through the array - using the '<<' and '>>' to surround the name helps identify odd side effects (such as newlines in names). I did double check that the provided code produces the same result - it does. And I'm running on a MacOS X 10.6.3 with the stock Perl.
From the Perldoc on readdir:
If you're planning to filetest the return values out of a readdir, you'd better prepend the directory in question. Otherwise, because we didn't chdir there, it would have been testing the wrong file.
Debugged code:
#!/usr/bin/perl
use strict;
if ($ARGV[1]) {
die("Error: You can only monitor one directory at a time\n");
}
my $directory = $ARGV[0] || die "Error: No directory defined\n";
opendir(DIR, $directory) || die "Error: Can't open dir $directory: $!";
my @contents = readdir(DIR);
foreach my $item (@contents) {
print "\$item=$item\n";
print "$item is a file \n" if (-f $directory."/".$item);
print"$item is a dir\n" if (-d $directory."/".$item);
}
closedir (DIR);
I guess your @contents
has newlines at the end of the file. Try adding chomp
:
foreach $item(@contents) {
chomp($item);
next if (-d $item);
print"$item is a file\n";
}
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