chdir in perl

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

Replies are listed 'Best First'.
Re: chdir in perl by jethro (Monsignor) on Sep 25, 2009 at 12:16 UTC
Using the backticks creates a subprocess and executes the shell command chdir (which probably doesn't exist) there, which doesn't change the environment in the process that is running your script the perl function chdir() works as intended. Check if the path in $mpath really exists and you have the rights to chdir to it UPDATED three times. Sloppy writing and code reading by me	[reply]
Re: chdir in perl by merlyn (Sage) on Sep 25, 2009 at 14:28 UTC
$mpath = `/vobs/package134/inttools/modules/unixtools/srce/whichPat +h $m`; ... if(! chdir($mpath)){ [download] I'm betting there's a newline on the end of $mpath. Since newline is a valid character within (and therefore at the end of) a path, the chdir() function cannot ignore it, and will look for a path that ends in newline, which you probably don't have. Consider a `chomp` on $mpath. -- Randal L. Schwartz, Perl hacker The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.	[reply] [d/l] [select]
Re^2: chdir in perl by Anonymous Monk on May 05, 2011 at 00:15 UTC
I'm betting there's a newline on the end of $mpath. Since newline is a valid character within (and therefore at the end of) a path, the chdir() function cannot ignore it, and will look for a path that ends in newline, which you probably don't have. Consider a chomp on $mpath. Great catch! You just solved an hour-long headscratching for me!	[reply]
Re: chdir in perl by tbone1 (Monsignor) on Sep 25, 2009 at 12:33 UTC
Okay, maybe I'm misreading this, BUT: It seems as if you are doing a `chdir $mpath`; which shells out to change the directory to the value of $mpath. Then you try to a chdir($mpath) ... which seems redundant. One thing: are all the values of $mpath ones that would work fine on a chdir? Meaning, no spaces, no tabs, etc? Just a though, because I've been bitten by that myself. -- tbone1, YAPS (Yet Another Perl Schlub) And remember, if he succeeds, so what. - Chick McGee	[reply]
Re: chdir in perl by repellent (Priest) on Sep 25, 2009 at 15:45 UTC
Use chdir instead. I would recommend this: `use Cwd qw(chdir);` [download] to keep `$ENV{PWD}` updated as you `chdir()`.	[reply] [d/l] [select]
Re^2: chdir in perl by raghvens (Novice) on Sep 29, 2009 at 04:43 UTC
Dear All, Thanks for your concerns and suggestions. The idea of $mpath i.e., when I execute this command: `/vobs/package134/inttools/modules/unixtools/srce/whichPath $m :: I will get the output as /vobs/package183/psappat/modules/<module name, that is having the $m value in the foreach loop>, So now I want to cd into this module, and then cd into confm folder, Here in this path/location, My intention is to check whether post_REFERENCED_to_EXPERIMENTAL file exists? and if so, find the link attached to this file. My concern is still I am not able to CHDIR into module. Please suggest. Modified Script: use Cwd qw(chdir); open(LS, "/home/raghvens/52xxmodulelist.txt") or die $!; @modlist = <LS>; @mpath = " "; foreach $m (@modlist) { print "\nProcessing $m .. \n"; $mpath = `/vobs/package134/inttools/modules/unixtools/srce/whichPat +h $m`; print "\nModule Path is $mpath \n"; chomp($mpath); $path = `chdir $mpath`; # or die "Can't cd into module path:$mpath +\n"; print "\nCurrent Path is $path"; if(! chdir($mpath)){ print "\n cannot change the working directory \n"; } `chdir confm`; $file = "post_REFERENCED_to_EXPERIMENTAL"; @output = system ("ls -l $file"); print "YES, Link is present" if $_ =~ /\-\>/ ; } [download] This is the output of the script: `Processing atp .. Module Path is /vobs/package183/psappat/modules/atp post_REFERENCED_to_EXPERIMENTAL: No such file or directory Current Path is Processing atpctm .. Module Path is /vobs/package183/psappat/modules/atpctm post_REFERENCED_to_EXPERIMENTAL: No such file or directory` [download]	[reply] [d/l] [select]
Re^3: chdir in perl by ig (Vicar) on Sep 29, 2009 at 07:18 UTC
Why do you think chdir is not working? Make sure you understand the previous responses. They all provide good advice and relevant information. To re-iterate: you should use the chdir function rather than executing the chdir command in a sub-process. But I wouldn't use chdir myself. I would do something more like the following: use strict; use warnings; open( my $fh, "/home/raghvens/52xxmodulelist.txt" ) or die $!; foreach my $m (<$fh>) { chomp($m); print "\nProcessing \"$m\" .. \n"; my $path = `/vobs/package134/inttools/modules/unixtools/srce/which +Path $m`; chomp($path); $path .= '/confm/post_REFERENCED_to_EXPERIMENTAL'; print "\tChecking for link \"$path\"\n"; print "YES, Link is present" if(-l $path); } [download]	[reply] [d/l]
Re^4: chdir in perl by raghvens (Novice) on Sep 30, 2009 at 13:45 UTC
Re^3: chdir in perl by raghvens (Novice) on Sep 29, 2009 at 05:28 UTC
Strange part is that, manually i am able to cd into all modules and respective confm folder to see the properties of the post_REFERENCED_to_EXPERIMENTAL file!!!	[reply]
Re: chdir in perl by newbieperl (Initiate) on Mar 13, 2017 at 16:59 UTC
HI I am new to perl..I am trying to run my script on a windows box. I need to change the script directory to my current path. please help	[reply]
Re^2: chdir in perl by hippo (Archbishop) on Mar 13, 2017 at 17:25 UTC
Have you noticed how most of the other responses in this thread mention the chdir function? That's probably worth investigating. If that doesn't solve your problem you will need to be much more specific in its description. See How do I post a question effectively? and SSCCE for guidance.	[reply]