Text Processing Unix Commands
Text processing Unix commands are those affecting text and text files. For example cut command in Unix, paste command in Unix, cmp command in Unix, sort command in Unix, comm command in Unix, head command in Unix, tail command in Unix, wc command in Unix, diff command in Unix, grep command in Unix are few in the list. While editing files, you may lose track of what changes you have made to which files.
In this article, we will cover commands that compare files.
cut command in Unix
- Cut selected fields of each line of a file.
- It can be used to cut parts of a line by byte position, character and field.
- It is necessary to specify option with command otherwise it gives error.
SYNTAX:
cut OPTION... [FILE]Option | Use |
-b | Bytes, extract the specific bytes |
-c | Characters, extract the specific characters |
-d | Delimiter, use the mentioned delimiter |
-f | Fields, extract only these fields |
Example:
List without ranges:
$ cat test.txt Learn Daily Study Smart Grow
$ cut -b 1,2,3 test.txt Lea Stu Gro
List with ranges:
$ cut -b 1-3,5-7 test.txt Lean D Stuy S Gro
Use -d option ,consider space as a field separator or delimiter:
$ cut -d " " -f 1 test.txt Learn Study Grow
paste command in Unix
- Merging the corresponding lines of given files
- It is used to join files horizontally (parallel merging)
SYNTAX:
$ paste [Option] file1 file2Example:
$cat file1.txt class Percent
$cat file2.txt 10th Pass
$paste file1 file2 class 10th Percent Pass
head command in Unix
- Display the top count lines of files or piped data to standard output.
- It displays 10 lines by default
SYNTAX:
head [-count] [file ...] Options | Use |
-n | “n” is number of lines |
-c | “c” is number of bytes |
-f | Follow the change in the file |
-s | Sleep interval |
Display Specific number of lines using head command
the OPTIONS “-n” where n is an integer displays the specific number of lines of the file.
SYNTAX: $ head -n filename.txt or $ head - filename.txt
Example:
$ head -n 15 file1.txt $ head -15 file1.txt
Display Specific number of bytes using head command
the OPTIONS “-c” displays the specific number of bytes of the file.
SYNTAX: $ head -c filename.txt
Example:
$ head -c 150 file1.txt
Display content of mutiple file using head command
Head command displays first 10 lines (by default) of each file when multiple files are provided as input to it.
SYNTAX: $ head filename1.txt filename2.txt
to view a different number of lines use “-n” option.
Example:
$ head -n 15 file1.txt file2.txt
tail command in Unix
-
- Display the last count lines of files or piped data to standard output.
- It displays 10 lines by default
SYNTAX: tail [OPTIONS].. [FILE]..
| Options | Use |
| -n | “n” is number of lines |
| -c | “c” is number of bytes |
| -f | Follow the change in the file |
| -s | Sleep interval |
for more on options, refer here
Display Specific number of lines from last using tail command
the OPTIONS “-n” where n is an integer displays the specific number of lines of the file.
SYNTAX: $ tail -n <INTEGER> filename.txt or $ tail -<INTEGER> filename.txt
Example:
$ tail -n 15 file1.txt $ tail -15 file1.txt
Display Specific number of bytes from last using tail command
the OPTIONS “-c” displays the specific number of bytes of the file.
SYNTAX: $ tail -c <INTEGER> filename.txt
Example:
$ tail -c 150 file1.txt
Display content of mutiple files
Tail command displays last 10 lines (by default) of each file when multiple files are provided as input to it.
SYNTAX: $ tail filename1.txt filename2.txt
to view a different number of lines use “-n” option.
Example:
$ tail -n 15 file1.txt file2.txt
Use tail with Other Commands in Unix
The tail command can be used in combination with other commands in unix.
Example:
tail -f error.log | grep 'message'