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

learn more… | top users | synonyms

5
votes
1answer
2k views

How can I match the page break character in a regular expression?

Nano calls it ^L, but of course, typing something like $ grep -v "^\^L" file doesn't work. Its unicode codepoint is 000C. How can I match it in a regular expression?
5
votes
5answers
171 views

Run `grep` excluding a file in a specific path

I want to exclude the file ./test/main.cpp from my search. Here's what I'm seeing: $ grep -r pattern --exclude=./test/main.cpp ./test/main.cpp:pattern ./lib/main.cpp:pattern ./src/main.cpp:pattern ...
5
votes
2answers
153 views

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
5
votes
5answers
371 views

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 ...
5
votes
2answers
6k views

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 ...
5
votes
2answers
3k views

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 ...
5
votes
3answers
174 views

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 ...
5
votes
5answers
1k views

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 ...
5
votes
1answer
2k views

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
votes
1answer
3k views

What does \bi\b mean in a grep pattern?

What does this command do? grep "\bi\b" linux.txt What is it searching for?
5
votes
1answer
1k views

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
votes
1answer
3k views

Is GREP_OPTIONS= --color=always ignored?

I was playing around with setting GREP_OPTIONS and couldn't get it to work. Just curious as to why. Simple test commands output: richard@ubuntu:~$ echo $GREP_OPTIONS richard@ubuntu:~$ ...
5
votes
1answer
117 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 ...
5
votes
3answers
210 views

How to find files containing two strings in different lines

A real example is: I have a Python file util.py, and I changed one of the function name from foo to bar. There might be other files using foo as function name and they are irrelevant. I want to ...
5
votes
1answer
642 views

What's the difference between \b and \< in the grep command

In the man page of grep, I see The symbols \< and \> respectively match the empty string at the beginning and end of a word. The symbol \b matches the empty string at the edge of a ...
5
votes
2answers
2k views

Why pidof and pgrep are behaving differently?

I have a init script in /etc/init.d/myservice for initialize a service like this: ... start() { ... daemon /usr/sbin/myservice ... } stop() { ... pgrep myservice pidof myservice ps -ef ...
5
votes
3answers
511 views

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 ...
5
votes
2answers
8k views

Grep: search and replace full line

The command grep "foo" myfile.txt prints all matching lines in my file. Now I want to replace the full line with another string. How can I do that?
5
votes
3answers
9k views

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
votes
1answer
190 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 ...
5
votes
1answer
519 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
702 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 ...
5
votes
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 ...
5
votes
2answers
2k views

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
votes
3answers
280 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 ...
5
votes
4answers
234 views

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 ...
5
votes
1answer
570 views

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?
4
votes
6answers
1k views

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 ...
4
votes
6answers
4k views

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 ...
4
votes
3answers
896 views

How can I delete all text between curly brackets in a multiline text file?

Example: This is { the multiline text file } that wants { to be changed } anyway. Should become: This is that wants anyway. I have found some similar threads in the forum, but they don't seem ...
4
votes
4answers
998 views

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 ...
4
votes
4answers
1k 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 ...
4
votes
4answers
4k views

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: ...
4
votes
4answers
545 views

Grep first 50 lines of files for pattern

How might one search the first 50 lines of files in a directory for a given string? I'm specifically looking for which database table files (from mysqldump) define a specific field, but I don't want ...
4
votes
3answers
2k views

Show lines matching a pattern and the 4 lines before each

For example, from this file: CREATE SYNONYM I801XS07 FOR I8010.I801XT07 * ERROR at line 1: ORA-00955: name is already used by an existing object CREATE SYNONYM I801XS07 FOR ...
4
votes
6answers
280 views

grep with a lot of files which contains a lot of lines?

Imagine we have a lot of huge(30000 line)files: a.2014-05-06, a.2014-05-07, a.2014-05-08 and so on. I know that we can grep a line with word using this command: grep "word" a.* First I guess this ...
4
votes
2answers
1k views

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?
4
votes
2answers
3k views

How do regular expressions differ from wildcards used to filter files

While we use * to denote zero or more previous characters in grep, we use *.c to find all C files when we use it with the ls command like ls *.c. Could someone tell how the use of * differs in these ...
4
votes
2answers
16k views

using xargs to grep multiple patterns

I have a file that has terms I want to grep for, with each term being one line in the file. I was thinking I could do this with xargs. What I'm able to glean from examples from the man page like this ...
4
votes
6answers
172 views

Append something to each list in a file

I have a file, lists.txt, that looks like this: // stuff at beginning of file var list1 = new Array(); i = 0; list1[i++] = 'a'; list1[i++] = 'b'; ... list1[i++] = 'z'; var list2 = new Array(); i = ...
4
votes
3answers
383 views

Output to be saved in file named same as the input file [duplicate]

I have one input file and run some command but want the output to be saved with the same name as the input file has. I tried below command but it makes the output file blank: cat file1 | grep ...
4
votes
4answers
1k views

grep with logic operators

Is there a grep-like utility that will enable me to do grep searches with logic operators. I want to be able to nest and combine the logical constructs freely. For example, stuff like this should be ...
4
votes
2answers
3k views

Using grep -v on multiple arguments

Is there a simpler way to do this? grep -v foo file | grep -v bar There're probably very elegant ways to do it with egrep, but how to go with plain old grep? EDIT: grep -v 'foo\|bar' file seems to ...
4
votes
2answers
164 views

how to extract parts of file into separate files in linux using awk or grep or sed commands

I have text file as shown below: Input file1.txt ....................... cha21 1 3 5 nar cha21 2 3 6 piy cha23 2 3 5 ram cha23 3 ...
4
votes
4answers
173 views

Insert new lines with missing values (NA)

I would like to insert new lines in text files if there are missing values. I have for example the following text file (A.txt), for which line 5 is missing. In addition, as the file should have 12 ...
4
votes
5answers
4k views

grep for multiple strings in files, and then list the files in the order of size

I am in a folder with lots of .txt file, I would like to find all the files which contain both stringA and stringB (not necessarily on the same line), then list these files in the order of the size ...
4
votes
2answers
265 views

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 ...
4
votes
3answers
2k views

How to find first match in multiple files

Is there a way for the find command to search for the first match or occurrence of a string or pattern within each of multiple files? I've been using the usual syntax: find dir -iname '*.ext' -exec ...
4
votes
3answers
562 views

Use command grep and locate

How I can make the grep command locate certain words in the files specified by the routes found by the locate command? locate my.cnf | grep user (I want that grep command search the word "user" ...
4
votes
1answer
87 views

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?