Grep_fgrep

frep & grep commands in UNIX Anisha (31) Jaee (32) Amber (33) Nihar (34) Shanawaz (35)

Introduction •

•

•

Basically when we create a file in UNIX or in any OS, we always need a way to search whatever we want in that file. In UNIX basically grep, fgrep, sed, sh are different types of commands which are used for searching a pattern in an input file. Depending upon user needs this command gives output/search result from given file.

grep command • •

• • •

Used for searching & printing the specified pattern from input. It is the abbreviation for “Global search for regular expression & print”. Where “Global” means entire file or standard input. “regular expression” means metachar pattern. “print” means to print ‘em all .

•

Syntax for grep: grep [options] pattern file/s

• • • •

Here ‘pattern’ plays an important role. Consider a file named as demo.txt After Concatenate we have: $ cat demo.txt Anisha | 19 | F | 31 Jaee | 18 | F | 32 Amber | 18 | M | 33 Nihar | 18 | M | 34 Shanawaz | 18 | M | 35

•

$ cat demo.txt Anisha | 19 | F | 31 Jaee | 18 | F | 32 Amber | 18 | M | 33 Nihar | 18 | M | 34 Shanawaz | 18 | M | 35

• •

Input : $ grep Nihar demo.txt Output : Nihar | 18 | M | 34

•

List of controls: l

-i : Ignore case distinctions in both the PATTERN and the input files. Input : $ grep –i 19 demo.txt output : Anisha | 19 | F | 31



$ cat demo.txt Anisha | 19 | F | 31 Jaee | 18 | F | 32 Amber | 18 | M | 33 Nihar | 18 | M | 34 Shanawaz | 18 | M | 35

2. -n: Prefix each line of output with the line number within Its input file. Input : $ grep -n F demo.txt output : 1:Anisha | 19 | F | 31 2:Jaee | 18 | F | 32

•

$ cat demo.txt Anisha | 19 | F | 31 Jaee | 18 | F | 32 Amber | 18 | M | 33 Nihar | 18 | M | 34 Shanawaz | 18 | M | 35

3.-v: Invert the sense of matching, to select nonmatching lines Input : $ grep -v Amber demo.txt output : Anisha | 19 | F | 31 Jaee | 18 | F | 32 Nihar | 18 | M | 34 Shanawaz | 18 | M | 35

•

$ cat demo.txt Anisha | 19 | F | 31 Jaee | 18 | F | 32 Amber | 18 | M | 33 Nihar | 18 | M | 34 Shanawaz | 18 | M | 35

4. -c: Suppress normal output; instead print a count of matching lines for each input file. Input : $ grep -c M demo.txt Output : 3 5. -o: only-matching Show only the part of a matching line that matches PATTERN. Input : $ grep –o Amber demo.txt Output : Amber

•

$ cat demo.txt Anisha | 19 | F | 31 Jaee | 18 | F | 32 Amber | 18 | M | 33 Nihar | 18 | M | 34 Shanawaz | 18 | M | 35

•

Using Regular Expressions: 2.

Display results which starts in range which are given in pattern. Input : $ grep -i ‘^[a-j]’ demo.txt Output : Anisha | 19 | F | 31 Jaee | 18 | F | 32 Amber | 18 | M | 33

•

$ cat demo.txt Anisha | 19 | F | 31 Jaee | 18 | F | 32 Amber | 18 | M | 33 Nihar | 18 | M | 34 Shanawaz | 18 | M | 35

2. Display the results which starts with the given pattern. Input : $ grep -i “[n,s]” demo.txt Output : Nihar | 18 | M | 34 Shanawaz | 18 | M | 35 3. Display result which starts & ends with the given pattern Input : $ grep ‘A*r’ demo.txt Output : Amber | 18 | M | 33

•

$ cat demo.txt Anisha | 19 | F | 31 Jaee | 18 | F | 32 Amber | 18 | M | 33 Nihar | 18 | M | 34 Shanawaz | 18 | M | 35

4. Display result which ends with the given pattern Input : $ grep ‘35$’ demo.txt Output : Shanawaz | 18 | M | 35

grep command with PIPES: 3.

Search for the directories in given location. Input : $ ls –l | grep ‘^d’ Output :drwxrw-rw- 2 user group 1234 Mar 19 13:01 Desktop

drwxrw-rw- 4 user group 1234 Mar 19 13:01 Music drwxrw-rw- 2 user group 1234 Mar 19 13:01 Docs

2. Search for an extension of file. That is (.). But in grep treats dot as special character. Hence we have to put ‘ \ ’ before dot to take command literally. Input : $ ls –l | grep ‘\.txt’ Output: -rw-rw-rw- 2 user group 23 Mar 19 13:01 demo.txt

-rwxr—r-- 2 user group 12 Mar 19 13:01 demo1.txt

Fgrep Command  Fgrep

command stands for ‘fixed

grep’.  Means, you can only search for fixed strings without use of any regular expression.  Like grep also you can simply add pattern while search.



Syntax for fgrep: fgrep [option] pattern file



List of Options in fgrep:

4.

-l: Print the names of files with matching lines once, separated by new-lines. Does not repeat the names of files when the pattern is found more than once Input: $ grep Amber demo.txt output: demo.txt

•

$ cat demo.txt Anisha | 19 | F | 31 Jaee | 18 | F | 32 Amber | 18 | M | 33 Nihar | 18 | M | 34 Shanawaz | 18 | M | 35

l

-x: Print only lines matched entirely. input: grep –x Jaee | 18 | F | 32 demo.txt output: Jaee | 18 | F | 32

Summary  grep

& fgrep are two most important & vast commands in Unix, when it comes about searching elements, files or directories present in your computer hard disk.  Both commands are similar, they differ by fraction of margin.

Bibliography  Working

with ‘Unix’- vijay mukhi  Shell scripts- y. kanetkar  www.computerhope.com  www.wikipedia.com  www.unix.com  www.google.com

Thank You!!