Questions tagged [regular-expression]
Regular expressions are a means of matching a pattern of characters within a string.
2,836 questions
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sed: why my regex does not work correctly
So, I'm facing a curious issue with sed; I have reduced my problem down to the following. Why does
sed -e 's/\"\([^\"]*\)\">/\1/' <<< '["\{">'
return ["\{&...
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2
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89
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Perl RegEx one-liner that outputs all matches from one line of STDIN
Here is a silly example that effectively illustrates what I need:
echo '"this text", " ", "is in speech marks"' | perl -lne 'print "$1" if /"(.*?)"/'
...
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2
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3
answers
351
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sed: invalid usage of line address 0
I need to keep only last 30 days events in the log and remove other data.
Log has timestamp (date +%e/%b/%Y:%H:%M) and next line values like
01/Jan/2025:00:00
value1
value2
...
01/Jan/2025:06:45
...
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3
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2
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Embedded special characters skewing sed output
The Issue
I've been parsing a file with sed trying to tweeze out the desired data. This has worked fine for most lines in the file but there appears to be some embedded special characters that are ...
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0
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5
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Extract email addresses from line, with multiple email addresses per line
I have a text file that mixes names and email addresses, in a comma-separated list.
First Person <[email protected]>, Second Person <[email protected]>, Third <[email protected]>
...
- 6,095
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1
answer
140
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sed inplace in selective block
I have a dir containing logstash config files
these files have filter blocks, and sometimes nested child blocks
need to match whole filter block
filter { any text till final matching closing brace for ...
- 2,009
3
votes
6
answers
221
views
regex to find text plus trailing 10+ spaces; sum of two matches' lengths is part of matching condition
I'm trying to clean files that are copy/pasted versions of my Cygwin (mintty) terminal running bash1. Usually, the input and output are separated by a linefeed ('\n'), as expected. However, when I ...
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1
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Is there any way to see the string that was matched in grep?
I'm not talking about -o option.
Posix says:
The search for a matching sequence starts at the beginning of a string and stops when the first sequence matching the expression is found, where "...
- 99
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3
answers
103
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How to remove markdown links from headers with sed?
I'm trying to use sed to remove links like and leave just the title:
## [Some title](#some-title)
This is my command:
sed 's/^\(\#*\) *\[\([^\]]*\)\].*/\1 \2/'
I expect to have just the text without ...
- 10.4k
0
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0
answers
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Borg files in `~/.local/share/` occur a “dir_open: [Errno 13] Permission denied” error
General overview
With BorgBackup, I do a backup of my whole $HOME. However, some files (all located on ~/.local/share/) occur a rights error. Probably cause it’s ephemeral files belonging to root, I ...
- 1,529
1
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3
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How to delete lines with sed if they contain a phrase?
I tried this
sed -i '/^already satisfied$/d' loggocd.txt
but lines like this one
Requirement already satisfied: cryptography in /home/go/.pyenv/versions/3.9.1/lib/python3.9/site-packages
are not ...
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votes
1
answer
89
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How to extract an unknown number of file lines between two regex patterns?
For example I have file with many of lines and it has such part
...
pattern1
line1
line2
line3
pattern2
...
how can I extract line[1-3] via one-liner command (awk or something like that)?
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4
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Grep (BRE) on surrounding delimiters w/o consuming the delimiter? Counting delimiter-separated strings between filename and extension
I have a dataset of images labeled/classified by characteristics, where an image can have more than one label. I want to count how many of each identifier I have. A toy dataset is created below, with ...
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3
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191
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grep capture from beginning until first 2 chars found
I have this list:
list="aa bb cc dd ee ff ab cd ef"
What I'm trying so far:
$ grep -o "^[^cd]*" <<<"$list"
aa bb
Expected output:
$ grep -o "^[^cd]*" ...
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3
votes
3
answers
274
views
Sed - Help Matching with Multi-Line Match
I am fairly new to regexes and it appears I am missing something in my understanding. I have the following file, and I am trying to insert a value if it is missing.
The file looks like
[composefs]
...
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