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

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how to execute lines coming from a grep result?

I've got a text file with certain installation instructions, and I know I can grep for a unique occurrence in the file. For example, the text file has something like: MYDIR=`find /home/user -name ...
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1answer
677 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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How to find a position of a character using grep?

I need to identify the postion of a character in string using grep command. Example, the string is RAMSITALSKHMAN|1223333. grep -n '[^a-zA-Z0-9\$\~\%\#\^]' How do I find the position of | in the ...
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3answers
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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 ...
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2answers
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How to run grep on a single column?

I want to grep the output of my ls -l command: -rw-r--r-- 1 root root 1866 Feb 14 07:47 rahmu.file -rw-r--r-- 1 rahmu user 95653 Feb 14 07:47 foo.file -rw-r--r-- 1 rahmu user ...
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5answers
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Number of files not containing given string

I read the question about how to find out the number of files that contain a certain string. This is possible with grep -l "string" * | wc -l. Is it possible to invert this, finding the number of ...
5
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4answers
799 views

Replace a string containing newline characters

With the bash shell, in a file with rows like the following ones first "line" <second>line and so on I would like to replace one or more occurrences of "line"\n<second> with other ...
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3answers
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Recursive grep for words in a particular file type

I wanted a command line command to search all shell scripts in the filesystem for a particular word, so I asked around at work and got the following solutions: grep word `find / -name \*.sh ...
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Detecting pattern at the end of a line with grep

If I do: $ ls -R .: 4Shared/ Cloud/ ./4Shared: UFAIZLV2R7.part3.rar ./Cloud: UFAIZLV2R7.part2.rar.part UFAIZLV2R7.part1.rar.part UFAIZLV2R7.part4.rar.part If I want to list the .rar files only, ...
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4answers
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Find a string only in a specific file inside subdirectories

Let's say I need to find the function GetTypes() in all C# source file (.cs) the directories/subdirectories. I used grep -rn GetTypes *.cs, but I got an error with grep: *.cs: No such file or ...
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2answers
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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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3answers
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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
535 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\>' ...
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2answers
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How to grep on source code without catching comments

I search a way to grep on source code without having sometimes false-positive because of comments. For instance if I search on foo on this .c source code : /* * foo has changed [...] and is now a ...
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2answers
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Grep 'OR' regex problem

I am trying to use grep with a regex to find lines in a file that match 1 of 2 possible strings. Here is my grep: $ grep "^ID.*(ETS|FBS)" my_file.txt The above grep returns no results. However if I ...
5
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1answer
845 views

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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4answers
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How can I suppress output from grep, so that it only returns the exit status?

I have the grep command. I'm searching for a keyword from a file, but I don't want to display the match. I just want to know the exit status of the grep.
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4answers
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How to replace m part of Lines with n part of Lines?

I have a file "test" like this: RewiteEngine On RewriteCond %{REMOTE_ADDR} !^192\.168\.1\.7$ [NC] RewriteCond %{REMOTE_ADDR} !^192\.168\.1\.8$ [NC] RewriteCond %{REMOTE_ADDR} ...
5
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1answer
266 views

grepping foo and bar

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 ...
5
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2answers
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What params do I pass to grep to return only file names?

I'm trying to use grep to find a specific piece of text in a bunch of files on my web server. No problem, except that it returns way more information than I want! Ideally it would just return a list ...
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1answer
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Piping search term (not filename) to grep

I want to pick out certain lines containing a given number from a file. The file I want to search is called os_clusters/piRNA_clusters.bed. awk '{if (a[$0]++ == 0) {split($0,b,"."); ...
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3answers
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grep for multiple regexes, and count the number of occurences

Say, I have a file, and multiple regexes have to be searched in it and the number of matches for each regex has to be counted. Thus, I cannot combine the patterns: grep -Po ...
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2answers
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Why does a grep reboot the machine?

On a RHEL 6.5 Desktop, if I use: sudo grep -r foo /* my desktop reboots. Q: Why?? How to debug this? It's the third time my Desktop reboots because of this :D
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A shell script to write selected fields to a single line

I have a log file trace.log which prints the time stamp, thread name and Transaction method and transaction ID as below. 2014-01-23 15:50:41,724 [catalina-exec-35] INFO TRANSACTION getConnection ...
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4answers
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Why does grep not work with redirection?

Using the top command with redirection works fine: top > top.log Now I want to use grep to filter a certain line: top | grep "my_program" > top.log But the log file will remain empty. But ...
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3answers
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Robustly segmenting a csv file containing noisy data

Say I have a csv file with these columns: timestamp,cpu,memory An example of the shape of the actual data would be this chart: Having the data visualized in this way, it's easy for the human eye ...
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5answers
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Pattern matching across multiple lines

What is a quick and easy way to validate if the pattern "301 domaname.com 200" is present within BASH when spread across multiple lines of output? I was using something like the following: awk ...
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1answer
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Find all lines between a line matching a pattern and a line matching another pattern

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 didnt work. Input: kkkkkkkkkkk ...
5
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2answers
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Looking for a Java class in a set of JARs with find, unzip, grep

I was trying to find the JAR containing a Java Class. JARs are in zip format. My first attempt was: $ find -name "*3.0.6.RELEASE.jar" | xargs -l1 unzip -l \ | grep stereotype.Controller ...
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1answer
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What does \bi\b mean in a grep pattern?

What does this command do? grep "\bi\b" linux.txt What is it searching for?
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tr complains of “Illegal byte sequence”

I'm brand new to UNIX and I am using Kirk McElhearn's "The Mac OS X Command Line" to teach myself some commands. I am attempting to use tr and grep so that I can search for text strings in a regular ...
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1answer
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Using Modifiers of Perl-compatible Regex (PCRE) in grep

According to grep --help and man grep, we can use the -P option in order to interpret the pattern as a Perl regular expression (PCRE, to be precise), instead of the default POSIX basic regular ...
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1answer
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How can I keep color codes with grep input?

It I grep something twice: ... | grep foo | grep bar It seems foo is not highlighted. Infact, it seems grep removes colorcodes from its input; Any way to prevent this?
5
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1answer
115 views

Search for a text in Linux but don't display the complete line in results

I'm using grep to do this, like: grep someText file.log But this returns the complete line in results. If someText is found in the middle of a line I don't want to ouput the whole line, just the ...
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3answers
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Mac OS X find/grep generating “unknown --devices option”

I am entering a command I have done often with Linux, Unix perfectly fine but with Apple Mac OS X 10.8 (and probably before) I get a grep: unknown --devices option when I attempt to run the following ...
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3answers
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Search for values in 2 columns from CSV

I have a csv files with say 20 odd columns. I need to get the 14th and 15th column values where value in 14th column is say "VALUE1" and value in 15th column is "VALUE2". My condition gets satisfied ...
5
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1answer
135 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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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 ...
5
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1answer
394 views

counting multiple patterns in a single pass with grep?

I've written a grep loop to iteratively count DNA trinucleotides within a gzipped DNA fasta file containing DNA sequences e.g. declare -a tri=(AAA AAC AAG AAT CAA .. etc) for i in ${tri[@]} do ...
5
votes
1answer
554 views

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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1answer
2k views

How to use grep/ack with files in arbitrary encoding?

On my Linux desktop I have a UTF-8 locale. When I try to search some KOI8-R encoded files with grep (ack), it fails. If I manually encode the pattern into KOI8-R and pass that as an argument, it ...
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2answers
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Pattern Matching Exclude Duplicate Characters

Is there a regular expression for the following that matches characters in a character set but only once? In other words, once a character is found, remove it from the set. If grep cannot do this, ...
5
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3answers
226 views

I am trying to find a better/easier way to count alphabetic characters in a file or shell variable

I have a file containing the following text: we are going to write something 1 2 3 wc tells me I have 1 line 9 words and 38 characters. I'm looking to count the 26 letters only (a-z, no numbers or ...
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4answers
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Search a pattern and print preceding lines starting with another pattern

I need to grep for a pattern and once I find it, I need to look for another pattern preceding that and print all those lines in between those. Better example: 1 a 2 a 3 a 4 a 5 a 6 b 7 c 8 d 9 xyz ...
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1answer
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How can I search/browse in some process's memory?

I'm using MacOS X 10.7 and I'm not very familiar with unix. Is there a command for a search in some process's memory for a string?
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grep invading my ps [duplicate]

When I'm checking for some process, I usually write ps aux | grep myprocess And sometimes I get the output of eimantas 11998 0.0 0.0 8816 740 pts/0 S+ 07:45 0:00 grep myprocess if ...
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4answers
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How to remove all comments from a file?

I have a file with a few lines commented out: foo bar stuff #Do not show this... morestuff evenmorestuff#Or this I just want to print all the uncommented code: foo bar stuff morestuff ...
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4answers
577 views

Match two words that is on the same line

The command that I have prints out two of the lines whenever FW_6.0.0 is found, below is the code: grep -oP 'FW_6.0.0, (.*)$' file Below is the output, both has the same value of FW_6.0.0 ...
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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: ...
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6answers
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Remove lines that do not start with a pattern from a given set of patterns

I have a file that contains data like this: report aaaaaaaa - .. -th bbbbbbbbb -to ccccccccc .. --. Question: I want to remove any line that does not start with following strings : report ...