unlink fails to delete files with perculiar names

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

Replies are listed 'Best First'.
Re: unlink fails to delete files with perculiar names by BrowserUk (Patriarch) on Nov 22, 2011 at 09:51 UTC
If you had warnings enabled, you'd see that part of your filename is being taken as a perl variable for interpolation: `$targ = "D:/Users/Dave/Documents/Personal/CV/~$rriculum Vitae - 09 Jun +e 2007.doc";; Use of uninitialized value $rriculum in concatenation (.) or string at + (eval 17) line 1, <STDIN> line 10.` [download] Just escape the $ with \: `$targ = "D:/Users/Dave/Documents/Personal/CV/~\$rriculum Vitae - 09 Ju +ne 2007.doc";;` [download] And the subsequent unlink will likely work. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l] [select]
Re^2: unlink fails to delete files with perculiar names by Eliya (Vicar) on Nov 22, 2011 at 10:45 UTC
The OP doesn't say how `$targ` was set. It's merely speculation that he assigned it using a double-quoted literal. It might just as well have come from a readdir or whatever. Also, why would unlink have returned 1, as the OP states? That should only have happened in the (unlikely) case there also was a file `'D:/Users/Dave/Documents/Personal/CV/~ Vitae - 09 June 2007.doc'` around at the time of the unlink call.	[reply] [d/l] [select]
Re^3: unlink fails to delete files with perculiar names by BrowserUk (Patriarch) on Nov 22, 2011 at 11:02 UTC
It's merely speculation that he assigned it using a double-quoted literal Agreed. That's why likely work. It might just as well have come from a readdir But don't you have to combine the values from readdir with the path in order to get a fully qualified path? Could he be doing something like `$targ = "$path/$fname";`? why would unlink have returned 1, as the OP states? Not sure, but that construct looks suspect to me: `my($no) = unlink $targ \|\| carp "Unable to delete file $targ\n";`. What ends up in `$no` if unlink returns 0; the return value from `carp()`? With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l] [select]
Re^4: unlink fails to delete files with perculiar names by Anonymous Monk on Nov 22, 2011 at 11:06 UTC
Re^5: unlink fails to delete files with perculiar names by Eliya (Vicar) on Nov 22, 2011 at 12:11 UTC
Re^3: unlink fails to delete files with perculiar names by DaveARoberts (Acolyte) on Nov 22, 2011 at 16:38 UTC
in my full code I get the file name using File::Find. From a windows directory listing from the command line the file is invisible, also from an explorer window...and from the application (MS word in this case) that presumeably created this as a temporary file it is also invisible.	[reply]
Re^2: unlink fails to delete files with perculiar names by DaveARoberts (Acolyte) on Nov 22, 2011 at 16:34 UTC
I tried escaping the $ with a \ that did not work ....	[reply]
Re^3: unlink fails to delete files with perculiar names by BrowserUk (Patriarch) on Nov 22, 2011 at 16:51 UTC
Then I suggest you try `del "D:\Users\Dave\Documents\Personal\CV\~$rriculum Vitae - 09 June 2007.doc"` on a command line and see what error message is produced by the shell. Update: Having seen one of your other replies, try doing: `attrib -h -s -r "D:\Users\Dave\Documents\Personal\CV\~$rriculum Vitae +- 09 June 2007.doc"` [download] And then the unlink or `del`. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l] [select]
Re: unlink fails to delete files with perculiar names by Eliya (Vicar) on Nov 22, 2011 at 08:58 UTC
`my($no) = unlink $targ \|\| carp "Unable to delete file $targ\n";` [download] This doesn't explain your deletion problem, but you most likely meant `my $no = unlink $targ or carp "Unable to delete file $targ\n";` [download] As you have it, the carp would only ever fire if `$targ` is false (e.g. `""`), but not when the unlink failed.	[reply] [d/l] [select]
Re: unlink fails to delete files with perculiar names by moritz (Cardinal) on Nov 22, 2011 at 09:56 UTC
Just a speculation: the variable name looks like it could be an automatic backup file from MS Word, and might be locked by the Word process, and thus not (easily) removable. Can you delete the file simply by pressing `DEL` in the Windows Explorer? Perl 6 - second systems done right	[reply] [d/l]
Re^2: unlink fails to delete files with perculiar names by DaveARoberts (Acolyte) on Nov 22, 2011 at 16:40 UTC
I think you are right in that the file is an auto backup from word, and probably one that was orphaned some months back. Unfourtunatly the file cannot be seen in an explorer window, or from the dir command in a command window.	[reply]
Re^3: unlink fails to delete files with perculiar names by Anonymous Monk on Nov 23, 2011 at 13:47 UTC
Unfourtunatly the file cannot be seen in an explorer window, or from the dir command in a command window. hidden files require doing more than the default to see them	[reply]
Re^3: unlink fails to delete files with perculiar names by DaveARoberts (Acolyte) on Nov 23, 2011 at 13:43 UTC
Thinking more on this I think that you have touched on the source of the file (a temporary backup from an MS Office program - I have excel, word and powerpoint examples). If I try to delete a file using unlink with the application still open it complains (Permission denied). The code snippet is from a file replication utility. I think what has happened is that an oen file has been replicated, the original destroyed by the creating application, and then replaced by a subsequent replication event. The preventative cure is to prohibit the copy of a file with the pattern "/~$" in its path/name. The curative solution may be to delete any directory containing files with this pattern - and recreate what I want from a backup	[reply]
Re: unlink fails to delete files with perculiar names by Khen1950fx (Canon) on Nov 22, 2011 at 09:22 UTC
Using File::Overwrite: `#!perl use strict; use warnings; use File::Overwrite qw(overwrite_and_unlink); my $new_file = shift @ARGV; overwrite_and_unlink($new_file);` [download] Note: The file must be closed in order for this to work on Windows.	[reply] [d/l]
Re: unlink fails to delete files with perculiar names by Anonymous Monk on Nov 22, 2011 at 09:20 UTC
`$ dir /b ~$ File Not Found $ echo > "~$" $ dir /b ~$ ~$ $ perl -e " unlink '~$' or die $!" $ dir /b ~$ File Not Found $ notepad > "~$" $ dir /b ~$ ~$ $ perl -e " unlink '~$' or die $!" Permission denied at -e line 1. $ perl -e " unlink '~$' or die qq/ $! \n $^E / " Permission denied The process cannot access the file because it is being used by another process at -e line 1.`	[reply]
Re: unlink fails to delete files with perculiar names by ikegami (Patriarch) on Nov 22, 2011 at 18:06 UTC
unlink reports the file deleted (and $no is set to 1 indicating one file deleted) - but in reality the file still exists. That means a program still has the file open. The file is marked to be deleted and will be deleted as soon no program has the file open anymore. Windows doesn't have anonymous files like unix does.	[reply]
Re: unlink fails to delete files with perculiar names by salva (Canon) on Nov 22, 2011 at 09:52 UTC
Use some utility as Process Monitor to see what's going on at the OS level.	[reply]
Re: unlink fails to delete files with perculiar names by stefbv (Curate) on Nov 22, 2011 at 08:57 UTC
Quote the argument of unlink. `my($no) = unlink "$targ" \|\| carp "Unable to delete file $targ\n";` [download]	[reply] [d/l]
Re^2: unlink fails to delete files with perculiar names by salva (Canon) on Nov 22, 2011 at 09:05 UTC
Putting the variable inside quotes is useless in this context.	[reply]
Re^3: unlink fails to delete files with perculiar names by stefbv (Curate) on Nov 22, 2011 at 09:18 UTC
~~I think it is not useless it's about dealing with spaces in file names.~~ Update: Sorry, made some further tests and I was wrong.	[reply]
Re^4: unlink fails to delete files with perculiar names by salva (Canon) on Nov 22, 2011 at 09:45 UTC
Re: unlink fails to delete files with perculiar names by Marshall (Canon) on Nov 22, 2011 at 09:00 UTC
`unlink ($targ) \|\| carp "Unable to delete file $targ\n";` [download] Unlink is different than "delete". Can you provide more information about how and why "unlink" does not work?	[reply] [d/l]
Re^2: unlink fails to delete files with perculiar names by BrowserUk (Patriarch) on Nov 22, 2011 at 09:54 UTC
Unlink is different than "delete". Do stop pushing this pointless distinction. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply]


Perl: the Markov chain saw
	PerlMonks