Perl is a high-level, general-purpose, interpreted, dynamic programming language. It was originally developed by Larry Wall as a general-purpose Unix scripting language to make report processing easier, over a period with support from open source community, it has evolved and matured to be used for ...

learn more… | top users | synonyms

14
votes
2answers
5k views

What does ${1+“$@”} mean in a shell script, and how does it differ from “$@”?

In the Perl documentation, perlrun(1) suggests launching Perl scripts using a bilingual shell/Perl header: #!/bin/sh #! -*-perl-*- eval 'exec perl -x -wS $0 ${1+"$@"}' if 0; What does ${1+"$@"} ...
10
votes
2answers
106 views

Resource friendly way to indicate to user program is not hanging

I have a Perl script on a *nix system which, at one point, is processing 50,000 + lines of text. This takes some time. I am trying to find a resource friendly way to let the user know the program is ...
9
votes
4answers
1k views

Why is Perl installed by default with most Linux distributions?

Just curious. The title says it all: Why is Perl installed by default with most Linux distributions?
8
votes
6answers
1k views

Delete lines beginning with #

How do I delete lines beginning with a #, given that there can be whitespace on the left and right of the #? # Master socket provides access to userdb information. It's typically
8
votes
2answers
4k views

How to know reason of a process going to sleep state and wake it up?

When I do 'top' , I see my perl script process in 'S' state. Is there a way to know, what is making this perl process go in sleep state and ways to wake it up? Any way to debug to give more insights ...
7
votes
6answers
2k views

Is there any alternative to grep's -A -B -C switches (to print few lines before and after )?

grep -A 2 -B 3 prints 2 lines after the grep string and prints 3 lines before. grep -C 3 prints 3 Lines before and 3 lines after Unfortunately, the grep I'm using does not support these ...
7
votes
2answers
91 views

Using empty line as context “group-separator” for grep

I need grep output with context, in color, and blank lines as group separator. In this question, I learned how to define custom group-separator, and I have constructed my grep command like this: grep ...
7
votes
1answer
309 views

Is there a way to make perl -i not clobber symlinks?

A friend of mine points out that if you do: perl -pi.bak -e 's/foo/bar/' somefile when "somefile" is actually a symlink, perl does just what the docs say it will do: It does this by renaming ...
6
votes
4answers
1k views

How to remove multiple blank lines from a file?

I have some text-files I use to take notes in - just plain text, usually just using cat >> file. Occasionally I use a blank line or two (just return - the new-line character) to specify a new ...
6
votes
2answers
106 views

Sorting with Perl respecting Locale Settings

Following data needs to be sorted respecting the locale sort order: wird sin wär pêche war Über Uber péché peach There was nor problem by using sort $ sort < data peach pêche péché sin Uber ...
6
votes
3answers
5k views

How can I install perldoc on Ubuntu?

Ubuntu 10.10 comes with Perl 5.10.1 pre-installed, but strangely enough perldoc isn't part of the package. $ perldoc You need to install the perl-doc package to use this program. How can I make ...
6
votes
2answers
490 views

Special character '#' in Perl SSH command

I try to send command using SSH in my perl script with # but it gets truncated right at # Example: Input text is : $message = "Product ID # STK000134" The SSH command is : $execute=`ssh -q ...
6
votes
1answer
159 views

How can I replace a string in a file(s)?

Replacing strings in files based on certain search criteria is a very common task. How can I replace string foo with bar in all files in the current directory? do the same recursively for sub ...
5
votes
2answers
1k views

Replacing missing value blank space with zero

I have input.txt tab-delimited text file around 30K lines, I would like to check each row (s1..s30K lines) for missing value (i.e blank space) and fill the missing value with zero value.See out.txt ...
5
votes
3answers
2k views

Find files with same name but different content?

I want to generate a list of files that have: Same name Different content in a directory (including all children directories and content). How to do? Bash, perl, anything is fine. So, two ...
5
votes
1answer
152 views

Execute a command within 'sed'

I have a list of random memory addresses saved in a text file, and I need to sed them out, decode them, and save them back to my file. However, the decoding operation I'm trying to perform is handled ...
5
votes
1answer
3k views

Execute Nohup command with input

In UNIX, I have a process that I want to run using nohup. However this process will at some point wait at a prompt where I have to enter yes or no for it to continue. So far, in UNIX I have been doing ...
5
votes
3answers
970 views

Regex & Sed/Perl: Match word that ISN'T preceded by another word

I'd like to use sed or perl to replace all occurrences of a word that doesn't have a certain word in front of it. For example, I have a text file that contains a plot of a movie and I want to replace ...
5
votes
2answers
313 views

Remove unknown unicode character from textfiles - sed, other bash/shell methods

I need to search and replace all occurences of an unknown character in some files having the same name. Opening such files with vi, I read <91> code for that character. Opening them with nano, I ...
5
votes
2answers
169 views

Getting or cloning the users current terminal?

I have to work with a script that forks and launches an instance of xterm in order to display log output in one window and have an interactive interface in the other. Personally I prefer rxvt-unicode ...
4
votes
5answers
1k views

extract the 4th column from a csv file using unix command

I have a csv file formatted as below. "col1","col2","col3","col4" "1","text1","<p>big html text</p> ","4th column" "2","text2","<p>big2 html2 text2</p> ...
4
votes
2answers
932 views

How do you determine if AIX 5.3 has PERL installed?

Simply put, how do you determine if AIX 5.3 has PERL installed as non-root?
4
votes
6answers
96 views

Only show the lines that are in all textfiles at least once

a.txt cat a.txt a b x c b.txt cat b.txt d e a f the q: SOMEMAGICK *.txt a Q: how can I show only the lines that are in all *.txt files?
4
votes
2answers
116 views

run perl script with unknown perl location

I'm developing a perl script which expected to be downloaded by Mac users with a very small knowledge of shell, linux etc, let's say office managers and accountants. After the downloading the script ...
4
votes
2answers
5k views

Compare two file columns

I have long text files with space-delimited fields: cat file1.txt Id leng sal mon 25671 34343 56565 5565 44888 56565 45554 6868 23343 23423 26226 6224 77765 88688 87464 6848 66776 23343 63463 ...
4
votes
4answers
118 views

Howto find and move a text line inside a file?

I need to change a text line position inside a file; from one line position to another one, underneath a defined text. For example, I have the following text block (on /etc/pam.d/system-auth file) ...
4
votes
4answers
63 views

How to switch the first letters of two words?

$ echo 'foo bar' | sed SOMEMAGIC boo far $ echo 'one two' | sed SOMEMAGIC tne owo Q: in general, how can I replace the "b" from the "bar" to the "f" of the "foo"? And in reverse too, replace the "f" ...
4
votes
2answers
142 views

Replace string with sequential index

Can someone suggest an elegant way to accomplish this? Input: test instant () test instant () ... test instant () //total 1000 lines output should be: test instant1 () test ...
4
votes
2answers
124 views

Column mismatch and substituting

input.txt (tab-delimted) TTTTOTTT00000000008 RTTTT899 5.00E-28 TTTTOTTT00000000046 RTTTWRR 3.00E-31 TTTTOTTT00000000051 2.00E-11 TTTTOTTT00000000051 7.00E-12 TTTTOTTT00000000054 ...
4
votes
4answers
852 views

How can I remove a specific string from a file only if there are other lines in the file?

How can I remove a specific string from a file ONLY if there are other lines in the file? For example, don't touch this file: cat file.txt ASDF but remove "ASDF" from this file: cat file.txt ASDF ...
4
votes
1answer
134 views

Using Modifiers of Perl-compatible Regex (PCRE) in grep

According to grep --help and man grep, we can use the -P option in order to interpret the pattern as a Perl regular expression (PCRE, to be precise), instead of the default POSIX basic regular ...
4
votes
2answers
199 views

Trying to do arithmetic in Perl rename tool (Debian)

Supposed I have five mp3 files: 01-trackfoo.mp3 02-trackbar.mp3 03-trackbaz.mp3 04-trackabc.mp3 05-trackxyz.mp3 Now I give a quick listen to the files (just mplayer on console will do the trick) ...
4
votes
3answers
2k views

Help with piped program in sendmail's /etc/aliases

I'm trying some sort of auto-subscription via a homegrown script. I know it can be achieved by mailing lists such as Mailman but I also want to learn at the same time on how to do it by hand. Here's ...
4
votes
1answer
760 views

Renaming files to have lower case extensions with 'rename'

I'm trying to currently rename a large set of files and have been using quite kludgy methods to do so, such as: rename 's:(.*)\.MOV:$1.mov:g' *.MOV rename 's:(.*)\.JPG:$1.jpg:g' *.JPG What I'd ...
4
votes
3answers
3k views

How to filter IPv4 and IPv6 addresses?

echo "1.1.1.1" | awk '/[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*/ {print $1}' How can I filter IPv4 addresses in a script, and how can I filter IPv6 addresses. I mean more precisely then this so the oneliner ...
4
votes
4answers
6k views

invalid SSL_version specified at /usr/share/perl5/IO/Socket/SSL.pm line 332

Since I upgraded my PC from (k)ubuntu 12.04 to 12.10 I receive this error message when trying to send an email using sendemail. Installing an older version of IO::Socket::SSL is not an option. I ...
4
votes
6answers
313 views

What is the easiest way to check if column A and B values goes both ways with AWK? [closed]

What is the easiest way to check if column A and B values goes both ways? Output to check: Mike John John Mike Pamela Barbara Barbara Pamela Mike Paul Roger Paul Desired output Mike <-> ...
4
votes
1answer
249 views

Passing clicked links in rxvt to a script

I start my browser vimprobable in tabbed like so: "`tabbed -d > /tmp/tabbed.xid`; vimprobable2 -e `cat /tmp/tabbed.xid`" [1] I am then able to send all new instances of vimprobable to tabbed (and ...
4
votes
2answers
797 views

Parsing XML from a shell script

I have a datafile like this: <Key name="com.ahsay.afc.cpf.UserGroup" content="" allowMultiple="Y"> <Value name="rsv-id" inheritParentAttribute="Y" type="string" data="1328200856753" ...
3
votes
2answers
1k views

find files not matching list of filename patterns

I find myself needing to find and identify extraneous files (out of about 900K files on a 2T drive). There are lots of files that I want to keep, and I have filename patterns for these known good ...
3
votes
2answers
117 views

Passing quotes and full strings to bash -c or zsh -c

When I am in Perl and I call system(some_command), this invokes some_command on /bin/sh. I would like it instead to run some_command in another shell such as bash or zsh. One way of running ...
3
votes
3answers
952 views

Delete XML node containing certain element

I want to remove all Placemarks from a KML file that contain the element <tessellate>. The following block should be wholly removed: <Placemark> ...
3
votes
2answers
154 views

No idea how to troubleshoot Bugzilla email issue

I'm a complete n00b when it comes to Bugzilla (and complex perl applications in general) so don't assume any level of knowledge in that area. If I haven't documented it in this post, assume I haven't ...
3
votes
2answers
195 views

Bash error message on a mac using Perl

I'm trying to run basic functions on Perl (Mac) but I get the same error message all the time. I managed to run programs like the simple 'hello, world' example. They work fine: $ perl -w hello.pl ...
3
votes
2answers
340 views

Parsing a text-file table and aggregating information

I have long text file with the following columns, space-delimited: Id Pos Ref Var Cn SF:R1 SR He Ho NC cm|371443199 22 G A R Pass:8 0 1 0 0 ...
3
votes
3answers
165 views

extract only the substring after double quotes - grep

I have a file which is as below. <a href="http://firstlink.com" title="title1"> <a href="http://secondlink.com" title="title2"> <a href="http://thirdlink.com" title="title3"> <a ...
3
votes
2answers
351 views

How to convert a .txt subtitle file to .srt format?

I have a subtitle file, it looks like this: 00:00:44:" Myślę, więc jestem".|Kartezjusz, 1596-1650 00:01:01:Trzynaste Pietro 00:01:06:Podobno niewiedza uszczęśliwia. 00:01:10:Po raz pierwszy w ...
3
votes
1answer
111 views

When did Automake switch to using Perl

I tried to get remove Perl from my Ubuntu machine, but found that automake not only depends on Perl but itself is a Perl program. I read somewhere this was not always the case. Today I looked in the ...
3
votes
2answers
258 views

Print row contain maximum and minimum value

I need to read the file (contains 16K rows)and print the entire row if any of columns and all columns contains max value (100) and all columns contain min value (0).The ouput example is given ...
3
votes
2answers
525 views

Installing CPAN dists not in the Arch repos

There's a lot of CPAN distributions in the Arch repositories, but not all of them. How should I handle a situation when I need a dist that is not already in the repos? Should I use the cpan program ...