How to use "grep" shell command to show specific word from a line starting with a specific word.
Ex:
I want to print a string "myFTPpath/folderName/" from the line starting with searchStr in the below mentioned line.
searchStr:somestring:myFTPpath/folderName/:somestring
Something like this with awk:
awk -F: '/^searchStr/{print $3}' File
From all the lines starting with searchStr, print the 3rd field (field seperator set as :)
Sample:
AMD$ cat File
someStr:somestring:myFTPpath/folderName/:somestring
someStr:somestring:myFTPpath/folderName/:somestring
searchStr:somestring:myFTPpath/folderName/:somestring
someStr:somestring:myFTPpath/folderName/:somestring
AMD$ awk -F: '/^searchStr/{print $3}' File
myFTPpath/folderName/
Remember that grep isn't the only tool that can usefully do searches.
In this particular case, where the lines are naturally broken into fields, awk is probably the best solution, as #A.M.D's answer suggests.
For more general case edits, however, remember sed's -n option, which suppresses printing out a line after edits:
sed -n 's/searchStr:[^:]*:\([^:]*\):.*/\1/p' input-file
The -n suppresses automatic printing of the line, and the trailing /p flag explicitly prints out lines on which there is a substitution.
This matching pattern is fiddly – use awk in this fielded case – but don't forget sed -n.
You could get the desired output with grep itself but you need to enable -P and -o parameters.
$ echo 'searchStr:somestring:myFTPpath/folderName/:somestring' | grep -oP '^searchStr:[^:]*:\K[^:]*'
myFTPpath/folderName/
\K discards the characters which are matched previously from printing at the final leaving only the characters which are matched by the pattern exists next to \K. Here we used \K instead of a variable length positive lookbehind assertion.
I want to search Exact word pattern in Unix.
Example: Log.txt file contains following text:
aaa
bbb
cccaaa ---> this should not be counted in grep output looking for aaa
I am using following code:
count=$?
count=$(grep -c aaa $EAT_Setup_BJ3/Log.txt)
Here output should be ==> 1 not 2, using above code I am getting 2 as output.
Something is missing, so can any one help me for the this please?
Use whole word option:
grep -c -w aaa $EAT_Setup_BJ3/Log.txt
From the grep manual:
-w, --word-regexp
Select only those lines containing matches that form whole words. The test is that the matching substring must
either be at the beginning of the line, or preceded by a non-word constituent character.
As noted in the comment -w is a GNU extension. With a non GNU grep you can use the word boundaries:
grep -c "\<aaa\>" $EAT_Setup_BJ3/Log.txt
Word boundary matching is an extension to the standard POSIX grep utility. It might be available or not. If you want to search for words portably, I suggest you look into perl instead, where you would use
perl -ne 'print if /\baaa\b/' $EAT_Setup_BJ3/Log.txt
You can use a word boundary (\b) in regex to match an exact word. To enable extended regex, use the -E flag with grep.
Solution:
grep -E "\baaa\b" $EAT_Setup_BJ3/Log.txt
I want to grep \" as following text in file(abc) like:
$egrep -n "^\"$" abc
"CO_FA_SC_600212","2","\"HSE 48\" 48 CHIVALRY AVE"
But its not appearing how could i use egrep or grep to get the line.
grep -F 'special char' filename will search the lines which has special characters.
grep -Fn 'special char' filename gets the line number too.
man grep says,
-F, --fixed-strings: Interpret PATTERN as a list of fixed strings, separated by newlines, any of which is to be matched
Here are two alternatives:
grep -n "\\\\\"" filename
grep -n '\\"' filename
For the first one, two consecutive \\ act as a single \, and " was escaped by \, so \\" is passed to grep.
For the second one, \ is taken literally, so \\" is passed to grep
3 and 4 can be verified by echo "\\\\\"" and echo '\\"'
How do I grep tab (\t) in files on the Unix platform?
If using GNU grep, you can use the Perl-style regexp:
grep -P '\t' *
The trick is to use $ sign before single quotes. It also works for cut and other tools.
grep $'\t' sample.txt
I never managed to make the '\t' metacharacter work with grep.
However I found two alternate solutions:
Using <Ctrl-V> <TAB> (hitting Ctrl-V then typing tab)
Using awk: foo | awk '/\t/'
From this answer on Ask Ubuntu:
Tell grep to use the regular expressions as defined by Perl (Perl has
\t as tab):
grep -P "\t" <file name>
Use the literal tab character:
grep "^V<tab>" <filename>
Use printf to print a tab character for you:
grep "$(printf '\t')" <filename>
One way is (this is with Bash)
grep -P '\t'
-P turns on Perl regular expressions so \t will work.
As user unwind says, it may be specific to GNU grep. The alternative is to literally insert a tab in there if the shell, editor or terminal will allow it.
Another way of inserting the tab literally inside the expression is using the lesser-known $'\t' quotation in Bash:
grep $'foo\tbar' # matches eg. 'foo<tab>bar'
(Note that if you're matching for fixed strings you can use this with -F mode.)
Sometimes using variables can make the notation a bit more readable and manageable:
tab=$'\t' # `tab=$(printf '\t')` in POSIX
id='[[:digit:]]\+'
name='[[:alpha:]_][[:alnum:]_-]*'
grep "$name$tab$id" # matches eg. `bob2<tab>323`
There are basically two ways to address it:
(Recommended) Use regular expression syntax supported by grep(1). Modern grep(1) supports two forms of POSIX 1003.2 regex syntax: basic (obsolete) REs, and modern REs. Syntax is described in details on re_format(7) and regex(7) man pages which are part of BSD and Linux systems respectively. The GNU grep(1) also supports Perl-compatible REs as provided by the pcre(3) library.
In regex language the tab symbol is usually encoded by \t atom. The atom is supported by BSD extended regular expressions (egrep, grep -E on BSD compatible system), as well as Perl-compatible REs (pcregrep, GNU grep -P).
Both basic regular expressions and Linux extended REs apparently have no support for the \t. Please consult UNIX utility man page to know which regex language it supports (hence the difference between sed(1), awk(1), and pcregrep(1) regular expressions).
Therefore, on Linux:
$ grep -P '\t' FILE ...
On BSD alike system:
$ egrep '\t' FILE ...
$ grep -E '\t' FILE ...
Pass the tab character into pattern. This is straightforward when you edit a script file:
# no tabs for Python please!
grep -q ' ' *.py && exit 1
However, when working in an interactive shell you may need to rely on shell and terminal capabilities to type the proper symbol into the line. On most terminals this can be done through Ctrl+V key combination which instructs terminal to treat the next input character literally (the V is for "verbatim"):
$ grep '<Ctrl>+<V><TAB>' FILE ...
Some shells may offer advanced support for command typesetting. Such, in bash(1) words of the form $'string' are treated specially:
bash$ grep $'\t' FILE ...
Please note though, while being nice in a command line this may produce compatibility issues when the script will be moved to another platform. Also, be careful with quotes when using the specials, please consult bash(1) for details.
For Bourne shell (and not only) the same behaviour may be emulated using command substitution augmented by printf(1) to construct proper regex:
$ grep "`printf '\t'`" FILE ...
Use echo to insert the tab for you grep "$(echo -e \\t)"
grep "$(printf '\t')" worked for me on Mac OS X
A good choice is to use sed.
sed -n '/\t/p' file
Examples (works in bash, sh, ksh, csh,..):
[~]$ cat testfile
12 3
1 4 abc
xa c
a c\2
1 23
[~]$ sed -n '/\t/p' testfile
xa c
a c\2
[~]$ sed -n '/\ta\t/p' testfile
a c\2
(This answer has been edited following suggestions in comments. Thank you all)
use gawk, set the field delimiter to tab (\t) and check for number of fields. If more than 1, then there is/are tabs
awk -F"\t" 'NF>1' file
+1 way, that works in ksh, dash, etc: use printf to insert TAB:
grep "$(printf 'BEGIN\tEND')" testfile.txt
On ksh I used
grep "[^I]" testfile
The answer is simpler. Write your grep and within the quote type the tab key, it works well at least in ksh
grep " " *
Using the 'sed-as-grep' method, but replacing the tabs with a visible character of personal preference is my favourite method, as it clearly shows both which files contain the requested info, and also where it is placed within lines:
sed -n 's/\t/\*\*\*\*/g' file_name
If you wish to make use of line/file info, or other grep options, but also want to see the visible replacement for the tab character, you can achieve this by
grep -[options] -P '\t' file_name | sed 's/\t/\*\*\*\*/g'
As an example:
$ echo "A\tB\nfoo\tbar" > test
$ grep -inH -P '\t' test | sed 's/\t/\*\*\*\*/g'
test:1:A****B
test:2:foo****bar
EDIT: Obviously the above is only useful for viewing file contents to locate tabs --- if the objective is to handle tabs as part of a larger scripting session, this doesn't serve any useful purpose.
This works well for AIX. I am searching for lines containing JOINED<\t>ACTIVE
voradmin cluster status | grep JOINED$'\t'ACTIVE
vorudb201 1 MEMBER(g) JOINED ACTIVE
*vorucaf01 2 SECONDARY JOINED ACTIVE
You might want to use grep "$(echo -e '\t')"
Only requirement is echo to be capable of interpretation of backslash escapes.
These alternative binary identification methods are totally functional. And, I really like the one's using awk, as I couldn't quite remember the syntaxic use with single binary chars. However, it should also be possible to assign a shell variable a value in a POSIX portable fashion (i.e. TAB=echo "#" | tr "\100" "\011"), and then employ it from there everywhere, in a POSIX portable fashion; as well (i.e grep "$TAB" filename). While this solution works well with TAB, it will also work well other binary chars, when another desired binary value is used in the assignment (instead of the value for the TAB character to 'tr').
The $'\t' notation given in other answers is shell-specific -- it seems to work in bash and zsh but is not universal.
NOTE: The following is for the fish shell and does not work in bash:
In the fish shell, one can use an unquoted \t, for example:
grep \t foo.txt
Or one can use the hex or unicode notations e.g.:
grep \X09 foo.txt
grep \U0009 foo.txt
(these notations are useful for more esoteric characters)
Since these values must be unquoted, one can combine quoted and unquoted values by concatenation:
grep "foo"\t"bar"
You can also use a Perl one-liner instead of grep resp. grep -P:
perl -ne 'print if /\t/' FILENAME
You can type
grep \t foo
or
grep '\t' foo
to search for the tab character in the file foo. You can probably also do other escape codes, though I've only tested \n. Although it's rather time-consuming, and unclear why you would want to, in zsh you can also type the tab character, back to the begin, grep and enclose the tab with quotes.
Look for blank spaces many times [[:space:]]*
grep [[:space:]]*'.''.'
Will find something like this:
'the tab' ..
These are single quotations ('), and not double ("). This is how you make concatenation in grep. =-)
I have a log file which contains a number of error lines, such as:
Failed to add email#test.com to database
I can filter these lines with a single grep call:
grep -E 'Failed to add (.*) to database'
This works fine, but what I'd really like to do is have grep (or another Unix command I pass the output into) only output the email address part of the matched line.
Is this possible?
sed is fine without grep:
sed -n 's/Failed to add \(.*\) to database/\1/p' filename
You can also just pipe grep to itself :)
grep -E 'Failed to add (.*) to database' | grep -Eo "[^ ]+#[^ ]+"
Or, if "lines in interest" are the only ones with emails, just use the last grep command without the first one.
You can use sed:
grep -E 'Failed to add (.*) to database'| sed 's/'Failed to add \(.*\) to database'/\1'
Recent versions of GNU grep have a -o option which does exactly what you want. (-o is for --only-matching).
This should do the job:
grep -x -e '(?<=Failed to add ).+?(?= to database)'
It uses a positive look-ahead assertion, followed by the match for the email address, followed by a postivie look-behind assertion. This insures that it matches the entire line, but only actually consumes (and thus returns) the email address part.
The -x option specifies that grep should match lines rather than the whole text.
or python:
cat file | python -c "import re, sys; print '\r\n'.join(re.findall('add (.*?) to', sys.stdin.read()))"
-r option for sed allows regexps without backslashes
sed -n -r 's/Failed to add (.*) to database/\1/p' filename
If you just want to use grep and output only matching part of line
grep -E -o 'Failed to add (.*) to database'
Then maybe if you want to write it to a file
cat yourlogfile | grep -E -o 'Failed to add (.*) to database' >> outputfile
So as of grep utility -o is going to -o, --only-matching show only nonempty parts of lines that match'.
If you want to use grep, it would be more appropiate to use egrep;
About egrep
Search a file for a pattern using full regular expressions.
grep will not always have as complete of functionality for regex.