Questions tagged [perl]
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 graphics programming, system administration, network programming, finance, bioinformatics, and other engineering applications.
155
questions
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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 ...
- 245k
33
votes
1
answer
4k
views
What's with all the renames: prename, rename, file-rename?
On my Debian system (well, my LMDE system, but close enough), I have at least 3 different rename programs:
/usr/local/bin/rename : This is a Perl script, written by Tom Christiansen. Oddly enough, I ...
- 245k
9
votes
1
answer
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views
What are the different versions of the rename command? How do I use the Perl version?
This is a mess. How do I know which command to use when we expect Perl's rename with s/// sed-like syntax, when there're tons of different implementations of rename, that are different versions of the ...
- 34.2k
39
votes
7
answers
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Linux equivalent to PowerShell's "one-to-many" remoting
Coming from Windows administration, I want to dig deeper in Linux (Debian).
One of my burning questions I could not answer searching the web (didn't find it) is: how can I achieve the so called "one-...
- 2,964
32
votes
5
answers
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How to grep for text in a file and display the paragraph that has the text?
Below is the text in the file:
Pseudo name=Apple
Code=42B
state=fault
Pseudo name=Prance
Code=43B
state=good
I need to grep for "42B" and get the output from the above text like:
Pseudo name=...
- 421
61
votes
11
answers
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views
How to insert the content of a file into another file before a pattern (marker)?
File1 contents:
line1-file1 "1"
line2-file1 "2"
line3-file1 "3"
line4-file1 "4"
File2 contents:
line1-file2 "25"
line2-file2 "24"
Pointer-file2 "23"
line4-...
- 871
33
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2
answers
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Security implications of running perl -ne '...' *
Apparently, running:
perl -n -e 'some perl code' *
Or
find . ... -exec perl -n -e '...' {} +
(same with -p instead of -n)
Or
perl -e 'some code using <>' *
often found in one-liners ...
- 554k
21
votes
4
answers
115k
views
compare two columns of different files and print if it matches
I am using Solaris 10 and so grep options involving -f don't work.
I have two pipe-separated files:
file1:
abc|123|BNY|apple|
cab|234|cyx|orange|
def|kumar|pki|bird|
file 2:
abc|123|
kumar|pki|
...
- 231
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votes
3
answers
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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 ${1+"$@"} ...
- 5,585
9
votes
1
answer
2k
views
How can I extract/change lines in a text file whose data are separated into fields?
How can I manipulate field-based data from the commandline? For example
How can I print only lines whose Nth field is foo?
How can I print only lines whose Nth field isn't foo?
How can I print only ...
- 245k
26
votes
3
answers
31k
views
Substitute pattern within a file with the content of other file
I have a text file (devel.xml).
I added the word REPLACETHIS to it in order to replace this string with the content within a different file (temp.txt).
The closest thing I have is this:
sed -i -e "/...
- 381
25
votes
7
answers
69k
views
Repeat each line multiple times
Would like to have each line in a file repeated a fixed number of times.
e.g. have each line repeated four times:
a
b
c
becomes:
a
a
a
a
b
b
b
b
c
c
c
c
I've done some searching, and there are a ...
- 933
11
votes
13
answers
3k
views
How to collapse consecutive numbers into ranges?
Given a sorted input file (or command output) that contains unique numbers, one per line, I would like to collapse all runs of consecutive numbers into ranges such that
n
n+1
...
n+m
becomes
n,n+m
...
- 83.5k
10
votes
2
answers
2k
views
How exactly does perl's -0 option work?
According to man perlrun:
-0[octal/hexadecimal]
specifies the input record separator ($/) as an octal or
hexadecimal number. If there are no digits, the null character is
the separator....
- 245k
9
votes
7
answers
10k
views
What is the easiest way to add a string on the beginning of every line of the file from the command line?
I am looking for a way to add some string to the beginning of every line (same string for every line).
Not something customizable but rather something that will be easy to remember and available on ...
- 12.4k