CODEWITHSUNDEEP
linuxbashcut
Gero
Gero

Reputation: 157

cut -f multiple arguments

I have a variable ($var) that contains a series of numbers ordered and separated with commas. As an example: 3,31,35,57,85,108,120,130,193,234,266,354,369,406,430,438,472,490,503,553,579,591,629,670,715,742,768,792,813

My original plan was to use them for extracting a series of columns in a file1 by the next code: cat file1 | cut -f "$var"

The terminal warns me of a problem: "Argument list too long". My objective remains the same — which strategy/alternative may I follow? I require something that lets me obtain all the columns (saving them or not in a file). Using a loop or whatever could prevent me from doing it "manually/individually".

A (smaller) example of the desired output:

123  299    429
12   0      2 
0    0      2
4    15     20
4    22     27
3    2      7
0    0      0
61   155    77
8327 5961   10023
5    11     17 
5777 8840   5669 
10   3      1 
53   365    199 
1    0      3 
26   31     15 
1    0      0

Upvotes: 0

Views: 679

Answers (2)

tshiono
tshiono

Reputation: 22012

Assuming:

  • Your file1 contains huge number of columns separated by tab.
  • You want to select the columns listed in the bash variable "$var".
  • The list is too long to be accepted as a command line argument.

Then would you try the awk solution:

#!/bin/bash

var="3,31,35,57,85,108,120,130,193,234,266,354,369,406,430,438,472,490,503,553,579,591,629,670,715,742,768,792,813"
echo "$var" > list
# the "echo" command above is for the demonstration purpose only.
# please create a csv file "list" which contains the column list as "var".

awk '
    BEGIN {FS = OFS = "\t"}                     # assign the field separators to TAB
    NR==FNR {len = split($0, a, ","); next}     # read the file "list" and assign an array "a" to the list
    {
        result = $a[1]                          # 1st element of the column indexed by array a
        for (i = 2; i <= len; i++)              # loop over the column list
            result = result OFS $a[i]           # append the next element of the indexed column
        print result                            # print the record
    }
' list file1

We need to store the list of column numbers in a separate file "list" to avoid the Argument list too long error. I have tested with approx. 600KB list and it works.

Upvotes: 2

Raman Sailopal
Raman Sailopal

Reputation: 12867

Use awk:

awk -F, '{ print $4","$7 }' file1

In this example, we set the field delimiter to , with -F and then print the 4th and 7th fields/columns only.

Upvotes: 0

Related Questions