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

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What does the --color=auto option for GNU grep mean?

AFAICT, neither the man page for GNU grep, nor info grep, deigns to spell out what --color=auto means. I must be one of the very few people on the planet for which the meaning of this option is not ...
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Limit grep context to N characters on line

I have to grep through some JSON files in which the line lengths exceed a few thousand characters. How can I limit grep to display context up to N characters to the left and right of the match? Any ...
6
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1answer
887 views

inexact text search

Is there any utility like grep or even uniq but for inexact search or I should write it myself? I mean it will look at 90% (number may vary) matching, or smth like that. For example I have file with ...
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5answers
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Recursively search folder but exclude svn subfolder

I want to find all occurences of foo in a large file system maintained by SVN but I don't want to match anything contained in any .svn directory. I get immediate matches when I do grep -l -e 'foo' * ...
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1answer
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What is the opposite of “grep”?

Say I'm printing out a long series of strings, and instead of only showing lines containing a certain pattern (which one uses "grep" to do), how do I filter out certain patterns?
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1answer
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Why do I have to escape a “dot” twice?

I know that we can escape a special character like *(){}$ with \ so as to be considered literals. For example \* or \$ But in case of . I have to do it twice, like \\. otherwise it is considered ...
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Pipe find into grep -v

I'm trying to find all files that are of a certain type and do not contain a certain string. I am trying to go about it by piping find to grep -v example: find -type f -name '*.java' | xargs grep -v ...
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4answers
325 views

Count number of a substring repetition in a string

I have a file which contains a gene sequence such as: ...
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6answers
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Check if a variable contains only what I want, and nothing else

I'm writing a script to build a software from sources, and there's a --platforms option. I would like to allow the user to select multiple items, but I don't know how to prevent them from making a ...
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How to detect and delete lines containing ˆ@

I have a simple problem: In my file, the are lines containing the string ˆ@ˆ@ˆ@ˆ@ˆ@ˆ@. I just want to delete all lines with this string, using for example the sed or grep commands. And I would like ...
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Suppress 'file truncated' messages when using tail

I'm tailing a log file using tail -f messages.log and this is part of the output: Lorem ipsum dolor sit amet, consectetur adipiscing elit. Fusce eget tellus sit amet odio porttitor rhoncus. Donec ...
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1answer
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find words with all vowels in order from a file

I have a large dictionary file with 300,000+ words in it and I'm trying to find all words with the vowels aeiou in that order and have only exactly 5 vowels. My current attempt does not seem to be ...
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Using a perl compatible regex with GNU grep -P

I'm using this regex (?<=\[')[^,]* on a file containing the following line disk = ['OVS/sdasd/asdasd/asdasd/something.img, w'] I want that to return OVS/sdasd/asdasd/asdasd/something.img How do I ...
6
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1answer
124 views

Function to simplify grep with an often used log

First off, sorry if this is a painfully newbish question! I'm trying make a function that simplifies grepping a log I have to work with on a regular basis. I'd like to use extended regexp with it ...
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3answers
413 views

Empty a file without grep subsequently treating it like a binary file

Currently I have netcat piping output to tee which is writing to output.txt with nc -l -k -p 9100 | tee output.txt I want to monitor this output, so I'm watching it with tail -f | egrep -i 'regex' ...
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2answers
325 views

Why two almost idetical grep commands return different output: w/o and with filename

I have 2 almost identical greps: [Alex@localhost tmp]$ grep /bin/bash /etc/passwd root:x:0:0:root:/root:/bin/bash AlexL:x:500:500::/home/AlexL:/bin/bash user1:x:501:501:user1 ...
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1answer
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How to grep all lines where starting line ends with a pattern and ending line ends with another?

I want to start grepping from the lines that has CK at the end of line and stop grepping when the line has D at the end. I tried grep "$CK" "$D" file..txt, but it didn't work. Input: kkkkkkkkkkk ...
6
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3answers
119 views

generate links of pages with incrementing variable

consider the links http://unix.stackexchange.com/questions/tagged/linux?page=2&sort=newest&pagesize=15 ...
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2answers
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What is the best way to find a list of several strings within a large text file

The short, general question is: In Unix/Linux, what is the best way to find a list of several (about 150) strings within a large text file? I am asking this to all Unix/Linux experts as a general ...
6
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1answer
299 views

grep --exclude does not exclude my file

I am searching a dir for a particular string (to see all instances of where the string is present and in which files). However, I want to exclude one particular file from being searched. Here's what ...
6
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2answers
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What's the most efficient way to grep for two completely separate things and assign the values to separate variables?

CentOS 6.x I want to take the output from curl, grep for two completely separate strings, and assign their respective values as variables. What is the most efficient way to do this (without writing ...
6
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1answer
644 views

grepping foo and bar [duplicate]

I am looking for a command options for grep to find files with the occurences of foo and bar. Grepping with grep -r -e foo -e bar . shows files which have only foo or only bar and files which ...
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4answers
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grep for an alphanumeric strings of any length with a colon on each side

How would you grep for an alphanumeric strings of 1 to 50 characters (ideally, any length would work too) with a colon on each side – a typical result would be all the lines containing the string ...
6
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1answer
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How can I keep color codes with grep input?

If I use two consecutive grep commands, e.g.: echo "foo bar" | grep foo | grep bar Then the first pattern ("foo") is not highlighted. In fact, it seems that grep removes color codes from its input. ...
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2answers
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git grep colors differ from grep custom colors

I've setup grep colors in my ~/.bashrc : export GREP_COLORS='ms=01;34:mc=01;34:sl=:cx=:fn=35:ln=32:bn=32:se=36' They work for grep --color=auto grep --color=always Unfortunately, those custom ...
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1answer
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grep for words of no more than a certain length

I'm looking for a way to grep things like: i log for E M, i 1 f x i 0, I xi 1, 3 1,. simply based on number of characters. Nothing in that hypothetical output is longer than three characters. This ...
6
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2answers
360 views

Is there a archive of old man pages? specifically for the features available for grep in early 'ed'

This is just a bit of history rummaging... I'd like to know how different today's grep is to the original implementation, introduced by Ken Thompson in ed. which evolved to ex, which then became vi... ...
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1answer
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grep: Ignoring GREP_OPTIONS to search case-sensitive

I have set GREP_OPTIONS="--ignore-case --color" in ~/.bashrc as I normally want grep to work case-insensitive. However, there are times when I need grep to actually search case-sensitive, but the man ...
6
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3answers
683 views

Get files with a name containing a date value less than or equal to a given input date

One of my folders contains files in the following format: 3_20150412104422154033.txt 3_2015041211022775012.txt 3_20150412160410171639.txt 3_20150412160815638933.txt 3_20150413161046573097.txt ...
6
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1answer
350 views

Conditional grep without quiet option

I always thought the quiet (-q) option had to be used when using grep conditionally. But re-reading the man page it seems like it should work without it. So if you want to print matches and use it in ...
6
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2answers
363 views

Grepping for a block of text with parts that can be optional

I have multiple entries that describes an event in a very large log file, say A.log. I would like to do two things with the event entries in the log file: Count the number of occurrences of each ...
6
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1answer
252 views

What is the meaning of this test expression []? [duplicate]

I've seen someone use command: ps -ef | grep [h]ttpd and Output is: apache 25125 31006 0 21:54 ? 00:00:00 /usr/sbin/httpd apache 26869 31006 0 22:04 ? 00:00:00 ...
6
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1answer
335 views

List overlapping instances of a pattern

I'm trying to capture a string and the 21 characters preceding it then output this to a new file. This is what I'm using currently: grep -o ".\{21\}gt" ../data/fastadata.txt > primerdata.txt ...
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2answers
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Grep multiple pattern negative match

So I have a bunch of Apache logs with using the standard log format. I want to get all the log lines that did not come from a web crawler. So lets say I have a file robot_patterns with entries like ...
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2answers
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Some UTF-8 characters not being recognized by grep or sed

Trying to determine all characters in a file. The file sample consists of: a eɪ abandon əˈbændən ability əˈbɪləti able ˈeɪbəl able ˈeɪbl abortion əˈbɔrʃən abortion əˈbɔrʃn about əˈbaʊt above əˈbʌv ...
6
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1answer
975 views

Peculiar piping grep/head behavior

I'm helping the netadmin here with a perl regex to automate operating on some snapshots from our SAN and our scripts does stuff like this: varinit1=$(iscsiadm -m session | grep rbmsdata1 | head -n1 | ...
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2answers
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How can I filter those “Permission denied” from find output? [duplicate]

I started using sed recently. One handy way I use it is to ignore unimportant lines of a log file: tail -f example.com-access.log | sed '/127.0.0.1/d;/ELB-/d;/408 0 "-" "-"/d;' But when I try to ...
5
votes
3answers
459 views

Why does this one-liner fail to produce output? [duplicate]

The following produces nothing in bash: while true ; do upower -d ; sleep 1 ; done | grep percentage | uniq I've discovered that it doesn't matter what the last- or even the second to last- program ...
5
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4answers
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How to exclude some files not matching certain extensions with grep?

I want to output all lines containing the word OK recursively from a directory. But there are a few extensions which I need to exclude from the result: *~ *.map *.js except *.debug.js I tried: ...
5
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2answers
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How to use tail -f with grep to show surrounding lines

I would like to see the output in a logfile greped by only one domain but also the following two lines. Example: tail -f /var/log/apache2/modsec_audit.log |grep mydomain.de this shows all lines, ...
5
votes
3answers
245 views

egrep regular expression - same word in the beginning and end

I want to find all the lines that have the same word in the beginning and in the end of the line. For example: goodword fgdlakj 3t sfkl 43lk fkl goodword bad sfa;lk3t dgk;gs 34;kl ...
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4answers
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Match exact string using grep

I have a text file: deiauk 1611516 afsdf 765 minkra 18415151 asdsf 4152 linkra sfsfdsfs sdfss 4555 deiauk1 sdfsfdsfs 1561 51 deiauk2 115151 5454 4 deiauk 1611516 afsdf ddfgfgd luktol1 4545 4 9 luktol ...
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Grep a file on specific field

I have two files, let's say File1: Locus_1 Locus_2 Locus_3 File2: 3 3 Locus_1 Locus_40 etc_849 3 2 Locus_2 Locus_94 * 2 2 Locus_6 Locus_1 * 2 3 Locus_3,Locus_4 ...
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4answers
672 views

extract lines according to a particular column

I have a CSV file like CK,ck XYZ,xyz,xyzs ABC,abc,abcs PQR,pqr,pqrs LMN,lmn, IJK,ijk, I have to check if something is written in column 3 except whitespace, then display the whole line.the output ...
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2answers
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how to make alias to make grep command shorter [duplicate]

In my coding, I always do grep -rnIi "abcabc" . --color But, how to make an alias that can let me type only one word with my search string? Is that possible?
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2answers
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Printing lines from one file if part of them appears in another. Both files are millions of lines long

I have two files, let's call them 123.txt and 789.txt. 123.txt is 2.5M lines long, and 789.txt is 65M lines long. Is there any way to use grep or similar to keep any lines from 789.txt that contain ...
5
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2answers
400 views

How do you get fgrep to find the literal “--help”?

fgrep --help | fgrep "--help" returns just the whole fgrep --help, how do I return just the lines that have the literal "--help" in them? The quotes don't do anything, nor does \-\-help.
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2answers
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How to search for text in a file ignoring newlines?

I'd like to search for text that may be split over several lines in a file. A grep that would ignore line breaks and return the matching span of lines. e.g. I would be searching for is an example ...
5
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3answers
213 views

grep command giving error

I am using grep to filter out the contents on some patterns(genes in my case). For more info,here is the earlier link. Find pattern from one file listed in another My code(should work) but is not. ...
5
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3answers
1k views

difference between .* and * in regular Expression

I've a file named "test" that contains linux Unixlinux Linuxunix it's linux l...x now when i use grep '\<l.*x\>' , it matches : linux it's linux l...x but when i use grep '\<l*x\>' ...