grep is a command-line tool for searching text patterns in files

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4answers
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How do I check if a file already has line with “contents” in it?

I need to know if a file aready has line with contents X in it, if not append line. here's the code I've tried. if ! $(grep 'eval $(perl -I$HOME/foo/lib/perl5 -Mlocal::lib=$HOME/foo)' ~/.bashrc) then ...
13
votes
5answers
11k views

Adding numbers from the result of a grep

I run the following command: grep -o "[0-9] errors" verification_report_3.txt | awk '{print $1}' and I get the following result: 1 4 0 8 I'd like to add each of the numbers up to a running count ...
20
votes
2answers
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What is a “loop device” when mounting?

I am doing a mounting of an iso file and looking at this tutorial. They use the command: $ mount -o loop disk1.iso /mnt/disk I'm trying to understand the use of -o loop. So I have two questions: ...
1
vote
1answer
268 views

How can I grep through files whose name begins with `-`? [duplicate]

I've tried this. grep -r thanks * slave-iv grep: invalid option -- '@' Usage: grep [OPTION]... PATTERN [FILE]... Try `grep --help' for more information. Here's ...
33
votes
7answers
26k views

How to grep standard error stream (stderr)?

I am using ffmpeg to get the meta info of an audio clip. But I am unable to grep it. $ ffmpeg -i 01-Daemon.mp3 |grep -i Duration FFmpeg version SVN-r15261, Copyright (c) 2000-2008 Fabrice ...
8
votes
3answers
2k views

How do I take a list and remove it from a file?

I have a long list of domain names that I need to remove from /etc/remotedomains. They're probably not in any particular order in the file. Each domain is on one line. How could I iterate through the ...
12
votes
7answers
14k views

grep and tail -f?

Is it possible to do a tail -f (or similar) on a file, and grep it at the same time? I wouldn't mind other commands just looking for that kind of behavior.
10
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2answers
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What does ^d mean in ls -l | grep ^d?

When I do ls -l | grep ^d it lists only directories in the current directory. What I'd like to know is what does the caret ^ in ^d mean?
64
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7answers
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Is there a basic tutorial for grep, awk and sed? [closed]

I've been a Linux user for a while, and I've a pretty decent understanding of most the common command line utilities. However, ones that come up and up again in relation to programming are grep, awk, ...
11
votes
3answers
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How do I count the number of occurrences of a word in a text file with the command line?

I have a large JSON file that is on one line, and I want to use the command line to be able to count the number of occurrences of a word in the file. How can I do that?
6
votes
2answers
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How to make vertical bar | work in grep?

Here's an example of a grep command line I've tried: grep '(565172|565173|565175)' /var/log/cups/error_log It doesn't produce any output, even though all 3 values are in the file multiple times. I ...
7
votes
2answers
1k views

grep - why do brackets in grep pattern remove the grep process from ps results?

Why do brackets in a grep pattern remove the grep process from ps results? $ ps -ef | grep XXXX [...] XXXX [...] grep XXXX $ ps -ef | grep [X]XXX [...] XXXX
1
vote
3answers
513 views

Help with a find command

I have a bunch of directories. Inside these directories is a cover letter and a zip archive of work. I wanted to run a quick and easy query to open up all the cover letters so I can decide if it's ...
8
votes
4answers
11k views

grep — removing text after delimiter token

I have a file in which I need to eliminate everything after the first ; on every line. So a file like this: sdfsdsdf; fsdfsddf;sdfsd; Will result in this: sdfsdsdf fsdfsddf I have looked into ...
4
votes
1answer
282 views

Strings enclosed in '' are ignored when using grep

When I tried searching for a string within a file, the results didn't include those that were enclosed in single quotes. For example: grep -rn text folder/ The results didn't include strings the ...
51
votes
4answers
11k views

Convince grep to output all lines, not just those with matches

Say I have the following file: $ cat test test line 1 test line 2 line without the search word another line without it test line 3 with two test words test line 4 By default, grep returns each ...
16
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8answers
10k views

pgrep and pkill alternatives on mac os x?

Are there alternatives to pgrep and pkill commands on Mac OS X or should I just create aliases for them using other commands available for me?
17
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6answers
1k views

How can I highlight matches using GNU grep?

I have seen on some Linux, that grep is configured to highlight the match, and print the matching file. How can I configure grep to highlight matches?
11
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3answers
3k views

bash find xargs grep only single occurence

Maybe it's a bit strange - and maybe there are other tools to do this but, well.. I am using the following classic bash command to find all files which contain some string: find . -type f | xargs ...