How to cut first column (variable length) of a string in shell

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How to cut first column (variable length) of a string in shell ?

ex of string :

23006 help.txt

I need 23006 as output

Many ways:

cut -d' ' -f1 <filename # If field separator is space
cut -f1 <filename  # If field separator is tab
cut -d' ' -f1 <filename | cut -f1  # If field separator is space OR tab
awk '{print $1}' filename
while read x _ ; do echo $x ; done < filename

linux, Many ways: cut -d' ' -f1 <filename # If field separator is space cut -f1 <filename # If field separator is tab cut -d' ' -f1 <filename | cut -f1 # If field separator is space  Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Learn more Shell script : How to cut part of a string

cut -d " " -f1 test.txt

where test.txt contains your input line

cut command in Linux with examples, Engineering, Sorting, SQL, Stack, Strings, Tableau, Technical Scripter, TechTips, test_cat_june It can be used to cut parts of a line by byte position, character and field. Above cut command prints first seven characters of each line from the file. Most unix files doesn't have fixed-length lines. Linux-Shell-​Commands. Output the third through the last characters of each line of the file file.txt, omitting the first two characters. cut -d ':' -f 1 /etc/passwd. Output the first field of the file /etc/passwd, where fields are delimited by a colon (':'). The first field of /etc/passwd is the username, so this command will output every username in the passwd file.

This one works for me

cut -d' ' -f2-

7 UNIX Cut Command Examples of How to Extract Columns or , Learn how to use the Cut command to extract a vertical selection of columns or fields The following UNIX cut example will extract the first column of the class file: Do you need to learn UNIX or Linux, including how to read and write shell​  1. Select Column of Characters. To extract only a desired column from a file use -c option. The following example displays 2nd character from each line of a file test.txt. $ cut -c2 test.txt a p s. As seen above, the characters a, p, s are the second character from each line of the test.txt file. 2.

Grabbing the first [x] characters for a string from a pipe, One way is to use cut : command This will give you the first 8 characters of each line of output. <(command) , your characters will be in the shell variable REPLY . To build a string of variable length of characters has its own question here. +1 Don't mess with cryptic external utilities when the shell has built-in syntax for this. Maybe explore "${var##*:}" if you don't need to be portable to older shells. But don't omit the double quotes around variable interpolations unless you are specifically looking for whitespace tokenization. – tripleee Sep 6 '13 at 5:43

Substrings in Bash, When you plug in the variables (both the string and the flags), Bash will return to Keep in mind that the cut command is not 0-indexed, so the first item in the list indicates the starting index of the substring and L is the length of the substring. awk '{ print $2 }' Gets the second column of the file. rev prepares the string (reverses it). I don't think cut can remove last N characters, so this thing removes first N chars from the reversed string. cut -c 8-Removes the first 7 characters from the string. (found out by trial and error, needs verification)

10 Practical Linux Cut Command Examples to Select File Columns, Linux command cut is used for text processing. The following example displays only first field of each lines from grep "/bin/bash" /etc/passwd | cut -d':' -s -f1,6,7 --output-delimiter='#' The length of the link may change. I am parsing a very large csv file, where the entry of column 26 has to be of length 10. I can see that there are cases where there are no entries (which is fine), but also cases where the entries have length less than 10 or greater than 10, that has to be erroneous.

Comments
  • Somehow, with the cut option, when I piped in ps output, the only entries in the displayed results were the ones with the first column (as meant by the OP) being of length 5 and the ones with length 3 or 4 were not. There was a blank area before the displayed output, I guess this space is equal in line numbers (term height) as the above mentioned lines, with hidden 3 / 4 char wide first column entry. The awk way worked fine.
  • ps gives a formatted output. (like printf %5d would give.) So, when cut is using space as the delimiter, it sees the leading space (for smaller PID numbers) as delimiters. Hence it prints everything before the first space (which is nothing in that case.)
  • ah that makes sense, thanks.