|
GREP Command in Unix and Linux Examples |
About Grep :
grep is a command-line utility for searching plain-text data sets for lines that match a regular expression
|
Grep Linux Command |
Grep Linux Command Description |
|
grep book /etc/passwd |
command to search book in a file |
|
grep -i "book" /etc/passwd |
To ignore word case i.e match book, Book, BOOK and all other combination with the -i option:
|
|
grep -R "192.168.1.5" /etc/ |
You can search recursively i.e. read all files under each directory for a string “192.168.1.5” |
|
grep -w "book" file |
The grep command to select only those lines containing matches that form whole words i.e. match only book word:
|
|
egrep -w 'word1|word2' /path/to/file |
Use grep to search 2 different words |
|
grep -c 'word' /path/to/file |
The grep can report the number of times that the pattern has been matched for each file using -c (count) option |
|
grep -n 'root' /etc/passwd |
Pass the -n option to precede each line of output with the number of the line in the text file from which it was obtained |
|
grep -v mars /path/to/file |
You can use -v option to print inverts the match; To print all line that do not contain the word mars:
|
|
dmesg | egrep '(s|h)d[a-z]' |
show the name of the hard disk devices:
|
|
grep -i 'Model' /proc/cpuinfo or |
Display cpu model name: |
|
$ grep --color vivek /etc/passwd
|
force grep to display output in colors, enter:
|
|
$ grep -v -c this demo_file
|
how many lines that does not match the pattern
|
|
Grep Command |
Grep command Description |
|
grep -o -b "string" file.txt
|
Displaying the position of the matched string in the line The -b option allows the grep command to display the character position of the matched string in a file.
|
|
grep -B 2 "Error" file.txt
|
Displaying the lines before the match. In log file it will tell lines around the error lines to know the cause of the error. This will prints the matched lines along with the two lines before the matched lines.
|
|
grep -A 3 "Error" file.txt
|
Displaying the lines after the match. This will display the matched lines along with the three lines after the matched lines. |
|
grep -C 5 "Error" file.txt
|
Displaying the lines around the match This will display the matched lines and also five lines before and after the matched lines |
|
$ export GREP_OPTIONS='--color=auto' GREP_COLOR='100;8
|
It will set the color for Matched Line and pattern found will be color |
