The -q option of grep means "quiet": with this option grep gives a returncode 0 if it found the pattern and 1 of not. Additionally one doesn't have to get rid of the output as there is none. To use grep -q in a compound command use
Here is a little script, which accepts a filename and a pattern (in principle any regexp should work, but i haven't tested it with more complicated ones - there may arise problems with the shell interpreting it in this case) and prints out the number of occurrences:
The script makes use of a certain feature of sed: to change only the first ocurrence of the pattern in a substitute-operation, as long as the g-clause is not given. The command
will only change the first occurrence of "pattern", to change all one would have to write:
The inner loop "chops off" one occurrence of pattern after the other, until none is left. For every chop-off-operation a counter is increased.
Hello,
How do I use grep to find a pattern in a list of file and then display 5 lines after the pattern is matched
Eg:
I want to match the string GetPresentCode in all files in a folder and then see 4 lines following this match. I am not sure if grep is what should be used to achieve. Thanks!... (3 Replies)
Hello Everyone,
i need to read specific number of lines ( always serialized ; i.e from 10 to 20 or from 34 to 44 ) in a file , where the first line is found by grep 'ing a keyword.
example
file.txt
------------------------------------------------------------------
--header
this is the... (7 Replies)
All:
OS version HP-UX ga016a501 B.11.31 U ia64
from the command prompt -grep for 1 to 11 occurences of "," returns both rows
from the command prompt -grep for 11 occurences of "," returns 0 rows - should be 1 row.
Any ideas - why?
ga016a501 -> grep ',\{1,11\}' test3 | more ... (7 Replies)
hey guys,
I tried searching but most 'search and replace' questions are related to one liners.
Say I have a file to be replaced that has the following:
$ cat testing.txt
TESTING
AAA
BBB
CCC
DDD
EEE
FFF
GGG
HHH
ENDTESTING
This is the input file: (3 Replies)
Want to write a function that prints an error when passed a list of file names. If the file list is empty, print error "no file found", if there are more than one file, print "error more than one file found" (22 Replies)
Hi all,
The task I have sounds easy enough but my solution seems too much complicated and I would like some ideas/feedback on how to achieve the same goal with a more elegant solution on HP-UX B.11.23 (a grep with a regexp would be nice, I did not manage to do a working one :/ )
Here is my... (4 Replies)
Hi,
here are few lines present in the logs. I want to grep on Error and print few lines before and after Error word is found
line1
Line2
Line3
Error
Line4
Line5
Line6
Line7
I want the output to be
Line2
Line3
Error
Line5 (1 Reply)
URGENT HELP IS NEEDED!!
I am looking to move matching lines (01 - 07) from File1 and 77 tab the matching string from File2, to File3.txt. I am almost done but
- Currently, script is not printing lines to File3.txt in order.
- Also the matching lines are not moving out of File1.txt
... (1 Reply)
I am new to grep and Linux and am looking to see if grep can parse out a list of lines that have a difference of more than 10 seconds between the times on each line.
Example
2016-09-17 19:30:57 INFO: id: 4562079216, time: 2016-09-17 19:30:41,
2016-09-17 12:02:26 INFO: id:... (26 Replies)
Discussion started by: Markham
26 Replies
LEARN ABOUT V7
grep
GREP(1) General Commands Manual GREP(1)NAME
grep, egrep, fgrep - search a file for a pattern
SYNOPSIS
grep [ option ] ... expression [ file ] ...
egrep [ option ] ... [ expression ] [ file ] ...
fgrep [ option ] ... [ strings ] [ file ]
DESCRIPTION
Commands of the grep family search the input files (standard input default) for lines matching a pattern. Normally, each line found is
copied to the standard output; unless the -h flag is used, the file name is shown if there is more than one input file.
Grep patterns are limited regular expressions in the style of ed(1); it uses a compact nondeterministic algorithm. Egrep patterns are full
regular expressions; it uses a fast deterministic algorithm that sometimes needs exponential space. Fgrep patterns are fixed strings; it
is fast and compact.
The following options are recognized.
-v All lines but those matching are printed.
-c Only a count of matching lines is printed.
-l The names of files with matching lines are listed (once) separated by newlines.
-n Each line is preceded by its line number in the file.
-b Each line is preceded by the block number on which it was found. This is sometimes useful in locating disk block numbers by con-
text.
-s No output is produced, only status.
-h Do not print filename headers with output lines.
-y Lower case letters in the pattern will also match upper case letters in the input (grep only).
-e expression
Same as a simple expression argument, but useful when the expression begins with a -.
-f file
The regular expression (egrep) or string list (fgrep) is taken from the file.
-x (Exact) only lines matched in their entirety are printed (fgrep only).
Care should be taken when using the characters $ * [ ^ | ? ' " ( ) and in the expression as they are also meaningful to the Shell. It is
safest to enclose the entire expression argument in single quotes ' '.
Fgrep searches for lines that contain one of the (newline-separated) strings.
Egrep accepts extended regular expressions. In the following description `character' excludes newline:
A followed by a single character matches that character.
The character ^ ($) matches the beginning (end) of a line.
A . matches any character.
A single character not otherwise endowed with special meaning matches that character.
A string enclosed in brackets [] matches any single character from the string. Ranges of ASCII character codes may be abbreviated
as in `a-z0-9'. A ] may occur only as the first character of the string. A literal - must be placed where it can't be mistaken as
a range indicator.
A regular expression followed by * (+, ?) matches a sequence of 0 or more (1 or more, 0 or 1) matches of the regular expression.
Two regular expressions concatenated match a match of the first followed by a match of the second.
Two regular expressions separated by | or newline match either a match for the first or a match for the second.
A regular expression enclosed in parentheses matches a match for the regular expression.
The order of precedence of operators at the same parenthesis level is [] then *+? then concatenation then | and newline.
SEE ALSO ed(1), sed(1), sh(1)DIAGNOSTICS
Exit status is 0 if any matches are found, 1 if none, 2 for syntax errors or inaccessible files.
BUGS
Ideally there should be only one grep, but we don't know a single algorithm that spans a wide enough range of space-time tradeoffs.
Lines are limited to 256 characters; longer lines are truncated.
GREP(1)