Grep for String and Open at the Corresponding Line

Grep for String and open at the corresponding line

You can load your grep output in Vim's quickfix list with:

$ vim -q <(grep -rn --include="*.cpp" mystring)

Go to the next occurence with :cn and to the previous occurrence with :cp.

See :help -q and :help quickfix.

grep for a string in a line if the previous line doesn't contain a specific string

grep is really a line-oriented tool. It might be possible to achieve what you want with it, but it's easier to use Awk:

awk '
  /xyz/ && !skip { print }
                 { skip = /jkl/ }
' file

Read as: for every line, do

• if the current line matches xyz and we haven't just seen jkl, print it;
• set the variable skip to indicate whether we've just seen jkl.

How can I format my grep output to show line numbers at the end of the line, and also the hit count?

-n returns line number.

-i is for ignore-case. Only to be used if case matching is not necessary

$ grep -in null myfile.txt

2:example two null,
4:example four null,

Combine with awk to print out the line number after the match:

$ grep -in null myfile.txt | awk -F: '{print $2" - Line number : "$1}'

example two null, - Line number : 2
example four null, - Line number : 4

Use command substitution to print out the total null count:

$ echo "Total null count :" $(grep -ic null myfile.txt)

Total null count : 2

How to grep for lines which contain particular words in a log file?

If you store your patterns in a file, one per line, you can use grep -f file-with-patterns file-to-search.log

From the man page:

   -f FILE, --file=FILE
          Obtain  patterns  from  FILE,  one  per  line.   The  empty file
          contains zero patterns, and therefore matches nothing.   (-f  is
          specified by POSIX.)

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Edit 2018:

Since I wrote this, I have become aware of the following interesting edge cases:

• You can read the list of patterns from pipe using -f - (if you don't need stdin, i.e. you specified files on grep's command line) or -f <() (in any case)
• grep's performance starts to fail badly if hundreds of patterns are passed. If your use case is that insane, consider generating and immediately executing a sed (or some other language) script, although this could potentially have problems with overlapping patterns.

How to grep multi line string with new line characters or tab characters or spaces

@TLP was pretty close:

perl -0777 -nE 'say for map {s/^\s+|\s+$//gr} /\bdummy\(\s*"(.+?)"/gs' test.txt

test1
test2

Using

• -0777 to slurp the file in as a single string
• /\bdummy\(\s*"(.+?)"/gs finds all the quoted string content after "dummy(" (with optional whitespace before the opening quote)
  
  • the s flag allows . to match newlines.
  • any string containing escaped double quotes will break this regex
• map {s/^\s+|\s+$//gr} trims leading/trailing whitespace from each string.

Get line number while using grep

grep -n SEARCHTERM file1 file2 ...

How do you grep a file and get the next 5 lines

You want:

grep -A 5 '19:55' file

From man grep:

Context Line Control

-A NUM, --after-context=NUM

Print NUM lines of trailing context after matching lines.  
Places a line containing a gup separator (described under --group-separator) 
between contiguous groups of matches.  With the -o or --only-matching
option, this has no effect and a warning is given.

-B NUM, --before-context=NUM

Print NUM lines of leading context before matching lines.  
Places a line containing a group separator (described under --group-separator) 
between contiguous groups of matches.  With the -o or --only-matching
option, this has no effect and a warning is given.

-C NUM, -NUM, --context=NUM

Print NUM lines of output context.  Places a line containing a group separator
(described under --group-separator) between contiguous groups of matches.  
With the -o or --only-matching option,  this  has  no effect and a warning
is given.

--group-separator=SEP

Use SEP as a group separator. By default SEP is double hyphen (--).

--no-group-separator

Use empty string as a group separator.

grep: show lines surrounding each match

For BSD or GNU grep you can use -B num to set how many lines before the match and -A num for the number of lines after the match.

grep -B 3 -A 2 foo README.txt

If you want the same number of lines before and after you can use -C num.

grep -C 3 foo README.txt

This will show 3 lines before and 3 lines after.

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