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.
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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
105
votes
8
answers
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How do you list number of lines of every file in a directory in human readable format.
I have a list of directories and subdirectories that contain large csv files. There are about 500 million lines in these files, each is a record. I would like to know
How many lines are in each ...
- 1,295
61
votes
11
answers
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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-...
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How to "grep" for line length in a given range?
NOTE: This question is the complement of this Q&A: How to "grep" for line length *not* in a given range?
I need to get only the lines from a textfile (a wordlist, separated with newline)...
user90825
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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 ${1+"$@"} ...
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votes
9
answers
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How can you combine all lines that end with a backslash character?
Using a common command line tool like sed or awk, is it possible to join all lines that end with a given character, like a backslash?
For example, given the file:
foo bar \
bash \
baz
dude \
happy
...
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39
votes
17
answers
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Converting CSV to TSV
I have a number of large CSV files and would like them in TSV (tab separated format). The complication is that there are commas in the fields of the CSV file, eg:
A,,C,"D,E,F","G",I,"K,L,M",Z
...
user14755
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-...
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answers
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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 ...
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votes
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answers
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Replace multiline string in files
I have a number of files I want to update by replacing one multi-line string with another multi-line string. Something along the lines of:
* Some text,
* something else
* another thing
And I want ...
- 1,039
36
votes
9
answers
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How to delete the last column of a file in Linux
I want to delete the last column of a txt file, while I do not know what the column number is. How could I do this?
Example:
Input:
1223 1234 1323 ... 2222 123
1233 1234 1233 ... 3444 125
0000 5553 ...
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votes
2
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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 ...
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33
votes
1
answer
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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 ...
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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=...
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Why is Perl installed by default with most Linux distributions?
Why is Perl installed by default with most Linux distributions?
user23312