CUT

-

This command comes in handy when you need to extract (that is, "cut out") various fields of data from a data file or the output of a command. The general format of the cut command is
cut -cchars file



where chars specifies what characters you want to extract from each line of file. This can consist of a single number, as in -c5 to extract character 5; a comma-separated list of numbers, as in -c1,13,50 to extract characters 1, 13, and 50; or a dash-separated range of numbers, as in -c20-50 to extract characters 20 through 50, 
inclusive. To extract characters to the end of the line, you can omit the second 
number of the range; so 



cut -c5- data



 extracts characters 5 through the end of the line from each line of data and writes the results to standard output.








[root@server1 ~]# cat file9
The Unix operating system was pioneered by Ken

Thompson and Dennis Ritchie at Bell Laboratories

in the late 1960s.  One of the primary goals in

the design of the Unix system was to create an

environment that promoted efficient program

development.



[root@server1 ~]# cut -c5- file9
Unix operating system was pioneered by Ken

pson and Dennis Ritchie at Bell Laboratories

he late 1960s.  One of the primary goals in

design of the Unix system was to create an

ronment that promoted efficient program

lopment.




[root@server1 ~]# cut -c5 file9
U

p

h

d

r

l









$ who | cut -c1-8       Extract the first 8 characters

ashish

ashu

mahajan








[root@server1 ~]# who |cut -c1-8,18- 
root         2011-04-13 14:46 (192.168.1.2)
root         2011-04-13 15:25 (192.168.1.2)
ashiashi     2011-04-13 15:26 (192.168.1.2)
ashi         2011-04-13 15:27 (192.168.1.2)
















The -d and -f options are used with cut when you have data that is delimited by a particular character. The format of the cut command in this case becomes


cut -ddchar –ffields file





where dchar is the character that delimits each field of the data, and fields specifies the fields to be extracted from file. Field numbers start at 1, and the same type of formats can be used to specify field numbers as was used to specify character positions before (for example, 
-f1,2,8, -f1-3, -f4-).



So to extract the names of all users of your system from 
/etc/passwd, you could type the following:


$ cut -d: -f1 /etc/passwd     Extract field 1






root

cron

bin

uucp

ash

ashiashi

other







$ cut -d: -f1,6 /etc/passwd   >>>Extract fields 1 and 6

root:/

cron:/

bin:/

uucp:/usr/spool/uucp

asg:/

ashiashi:/users/ashiashi

other:/
















If the cut command is used to extract fields from a file and the -d option is not supplied, cut uses the tab character as the default field delimiter.

























If you have a string “one two three”, which shell command would you use to extract the strings?



echo $string | cut -d” ” -f1
echo $string | cut -d” ” -f2
echo $string | cut -d” ” -f3 




















How would you get the character positions 10-20 from a text file?



cat filename.txt | cut -c 10-20



or



cut -c10-20



 



 





What is use of “cut” command? Give some examples.



Cut – Utility used to cut/Strip out the required data/text from the source.



Cut can be used in three modes,



  Stripping by Character



     cut -c 1-3



  Striping by Byte length



     cut -b -1-72



Stripping by delimiter and fields.



     cut -d “|” -f1



Where   



-d “|” -> Delimiter used in input text to separate columns



-f1 -> Field/Column number  



While processing huge input files, Cut’s performance is far better than awk

 



 

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