A filter, such as the
UNIX cut command, is a program that processes an input stream of data
to produce an output stream of data. The input data may be fed into
the program's standard input or read from a file, and the output data
may be sent to standard output or sent to a file.
The UNIX cut command is used to extract a vertical selection of columns (character position) or fields from one or more files. The syntax for extracting a selection based on a column number is:
Here c tells us that we have to slice a column, and n is the number of the column.
Note : that column number start with number 1 rather than 0.
Example 1 - Cut column 1
The following UNIX cut example will extract the first column of the class file:
The syntax for extracting a selection based on a field number is:
where f stands for field and n represents the number of the field to extract. The default field delimiter is the tab character.
Example of field
This cut example will extract the second field of the class file and redirect standard output to the file class.lastname:
Changing the delimitter
We know that default delimitter is tab - what if we want to have a ":", then we can use -d option.
Eg.:
1. Write a unix/linux cut command to print characters by position?
The cut command can be used to print characters in a line by specifying the position of the characters. To print the characters in a line, use the -c option in cut command
The above cut command prints the fourth character in each line of the file. You can print more than one character at a time by specifying the character positions in a comma separated list as shown in the below example
This command prints the fourth and sixth character in each line.
2.Write a unix/linux cut command to print characters by range?
You can print a range of characters in a line by specifying the start and end position of the characters.
The above cut command prints the characters from fourth position to the seventh position in each line. To print the first six characters in a line, omit the start position and specify only the end position.
To print the characters from tenth position to the end, specify only the start position and omit the end position.
If you omit the start and end positions, then the cut command prints the entire line.
3.Write a unix/linux cut command to print the fields using the delimiter?
You can use the cut command just as awk command to extract the fields in a file using a delimiter. The -d option in cut command can be used to specify the delimiter and -f option is used to specify the field position.
This command prints the second field in each line by treating the space as delimiter. You can print more than one field by specifying the position of the fields in a comma delimited list.
The above command prints the second and third field in each line.
Note: If the delimiter you specified is not exists in the line, then the cut command prints the entire line. To suppress these lines use the -s option in cut command.
4. Write a unix/linux cut command to display range of fields?
You can print a range of fields by specifying the start and end position.
The above command prints the first, second and third fields. To print the first three fields, you can ignore the start position and specify only the end position.
To print the fields from second fields to last field, you can omit the last field position.
5. Write a unix/linux cut command to display the first field from /etc/passwd file?
The /etc/passwd is a delimited file and the delimiter is a colon (:). The cut command to display the first field in /etc/passwd file is
6. The input file contains the below text
Using the cut command extract the portion after the dot.
First reverse the text in each line and then apply the command on it.
References
The UNIX cut command is used to extract a vertical selection of columns (character position) or fields from one or more files. The syntax for extracting a selection based on a column number is:
$ cut -c n [filename(s)]
Here c tells us that we have to slice a column, and n is the number of the column.
Note : that column number start with number 1 rather than 0.
Example 1 - Cut column 1
$ cat class
A Johnson Sara
D Smith Tom
B Jones Mindy
D Anderson Bob
The following UNIX cut example will extract the first column of the class file:
$ cut -c 1 class
A
D
B
D
Extracting the field numberThe syntax for extracting a selection based on a field number is:
$ cut -f n [filename(s)]
where f stands for field and n represents the number of the field to extract. The default field delimiter is the tab character.
Example of field
This cut example will extract the second field of the class file and redirect standard output to the file class.lastname:
$ cut -f 2 class > class.lastnameNow seeing the file class.lastname
$ cat class.lastname Johnson Smith Jones Anderson
Changing the delimitter
We know that default delimitter is tab - what if we want to have a ":", then we can use -d option.
Eg.:
cut -d: blah blah
More Examples
We will see the usage of cut command by considering the below text file as an example> cat file.txt unix or linux os is unix good os is linux good os
1. Write a unix/linux cut command to print characters by position?
The cut command can be used to print characters in a line by specifying the position of the characters. To print the characters in a line, use the -c option in cut command
cut -c4 file.txt x u l
The above cut command prints the fourth character in each line of the file. You can print more than one character at a time by specifying the character positions in a comma separated list as shown in the below example
cut -c4,6 file.txt xo ui ln
This command prints the fourth and sixth character in each line.
2.Write a unix/linux cut command to print characters by range?
You can print a range of characters in a line by specifying the start and end position of the characters.
cut -c4-7 file.txt x or unix linu
The above cut command prints the characters from fourth position to the seventh position in each line. To print the first six characters in a line, omit the start position and specify only the end position.
cut -c-6 file.txt unix o is uni is lin
To print the characters from tenth position to the end, specify only the start position and omit the end position.
cut -c10- file.txt inux os ood os good os
If you omit the start and end positions, then the cut command prints the entire line.
cut -c- file.txt
3.Write a unix/linux cut command to print the fields using the delimiter?
You can use the cut command just as awk command to extract the fields in a file using a delimiter. The -d option in cut command can be used to specify the delimiter and -f option is used to specify the field position.
cut -d' ' -f2 file.txt or unix linux
This command prints the second field in each line by treating the space as delimiter. You can print more than one field by specifying the position of the fields in a comma delimited list.
cut -d' ' -f2,3 file.txt or linux unix good linux good
The above command prints the second and third field in each line.
Note: If the delimiter you specified is not exists in the line, then the cut command prints the entire line. To suppress these lines use the -s option in cut command.
4. Write a unix/linux cut command to display range of fields?
You can print a range of fields by specifying the start and end position.
cut -d' ' -f1-3 file.txt
The above command prints the first, second and third fields. To print the first three fields, you can ignore the start position and specify only the end position.
cut -d' ' -f-3 file.txt
To print the fields from second fields to last field, you can omit the last field position.
cut -d' ' -f2- file.txt
5. Write a unix/linux cut command to display the first field from /etc/passwd file?
The /etc/passwd is a delimited file and the delimiter is a colon (:). The cut command to display the first field in /etc/passwd file is
cut -d':' -f1 /etc/passwd
6. The input file contains the below text
> cat filenames.txt logfile.dat sum.pl add_int.sh
Using the cut command extract the portion after the dot.
First reverse the text in each line and then apply the command on it.
rev filenames.txt | cut -d'.' -f1
References
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