Cut is a command to extract portion of text from a file or from the given text.
Below are some of the examples based on a file test.txt whose contents are as below.
$ cat test.txt
cat command for file oriented operations.
cp command for copy files or directories.
ls command to list out files and directories with its attributes.
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1. Select Column of Characters
To extract only a desired column(in this case column2) from a file use -c option.
$ cut -c2 test.txt
a
p
s
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2. Select Column of Characters using Range
The following example extracts first 3 characters of each line.
$ cut -c1-3 test.txt
cat
cp
ls
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3. Select Column of Characters using either Start or End Position
The following specifies only the start position before the ‘-’. This example extracts from 3rd character to end of each line from test.txt file.
$ cut -c3- test.txt
t command for file oriented operations.
command for copy files or directories.
command to list out files and directories with its attributes.
The following specifies only the end position after the ‘-’. This example extracts 8 characters from the beginning of each line from test.txt file.
$ cut -c-8 test.txt
cat comm
cp comma
ls comma
The entire line would get printed when you don’t specify a number before or after the ‘-’ as shown below.
$ cut -c- test.txt
cat command for file oriented operations.
cp command for copy files or directories.
ls command to list out files and directories with its attributes.
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4. Select a Specific Field from a File
Instead of selecting x number of characters, if you like to extract a whole field, you can combine option -f and -d.
The following example displays only first field of each lines from /etc/passwd file using the field delimiter : (colon).
$ cut -d':' -f1 /etc/passwd
root
daemon
bin
sys
sync
games
bala
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5. Select Multiple Fields from a File
$ grep "/bin/bash" /etc/passwd | cut -d':' -f1,6
root:/root
bala:/home/bala
To display the range of fields specify start field and end field as shown below. In this example, we are selecting field 1 through 4, 6 and 7
$ grep "/bin/bash" /etc/passwd | cut -d':' -f1-4,6,7
root:x:0:0:/root:/bin/bash
bala:x:1000:1000:/home/bala:/bin/bash
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6. Select Fields Only When a Line Contains the Delimiter
In our /etc/passwd example, if you pass a different delimiter other than : (colon), cut will just display the whole line.
In the following example, we’ve specified the delimiter as | (pipe), and cut command simply displays the whole line, even when it doesn’t find any line that has | (pipe) as delimiter.
$ grep "/bin/bash" /etc/passwd | cut -d'|' -f1
root:x:0:0:root:/root:/bin/bash
bala:x:1000:1000:bala,,,:/home/bala:/bin/bash
But, it is possible to filter and display only the lines that contains the specified delimiter using -s option.
The following example doesn’t display any output, as the cut command didn’t find any lines that has | (pipe) as delimiter in the /etc/passwd file.
$ grep "/bin/bash" /etc/passwd | cut -d'|' -s -f1
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7. Complement :
Select All Fields Except the Specified Fields
using –complement option.
The following example displays all the fields from /etc/passwd file except field 7
$ grep "/bin/bash" /etc/passwd | cut -d':' --complement -s -f7
root:x:0:0:root:/root
bala:x:1000:1000:bala,,,:/home/bala
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8. Output Delimiter:
To change the output delimiter use the option –output-delimiter as shown below. In this example, the input delimiter is : (colon), but the output delimiter is # (hash).
$ grep "/bin/bash" /etc/passwd | cut -d':' -s -f1,6,7 --output-delimiter='#'
root#/root#/bin/bash
bala#/home/bala#/bin/bash
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9. Change Output Delimiter to Newline
In this example, each and every field of the cut command output is displayed in a separate line. We still used –output-delimiter, but the value is $’\n’ which indicates that we should add a newline as the output delimiter.
$ grep bala /etc/passwd | cut -d':' -f1,6,7 --output-delimiter=$'\n'
bala
/home/bala
/bin/bash
----------------------------------------
10. Example of combining Cut with Other Unix Commands
$ ps axu | grep python | sed 's/\s\+/ /g' | cut -d' ' -f2,11-
2231 /usr/bin/python /usr/lib/unity-lens-video/unity-lens-video
2311 /usr/bin/python /usr/lib/unity-scope-video-remote/unity-scope-video-remote
2414 /usr/bin/python /usr/lib/ubuntuone-client/ubuntuone-syncdaemon
2463 /usr/bin/python /usr/lib/system-service/system-service-d
3274 grep --color=auto python
