如何在shell脚本中将几个shell变量传递给awk？

Question

I have written a shell script to get any column. The script is:

#!/bin/sh
awk '{print $c}' c=${1:-1}

So that i can call it as

ls -l | column 2

But how do i implement it for multiple columns? Say, it i want something like :

ls -l | column 2 3

Answer 1

In this case, I wouldn't use awk at all:

columns() { tr -s '[:blank:]' ' ' | cut -d ' ' -f "$@"; }

This uses tr to squeeze all sequences of whitespace to a single space, then cut to extract the fields you're interested in.

ls -l | columns 1,5,9-

Note, you shouldn't parse the output of ls .

Answer 2

awk -v c="3,5" '
    BEGIN{ split(c,a,/[^[:digit:]]+/) }
    { for(i=1;i in a;i++) printf "%s%s", (i==1?"":OFS), $(a[i]); print "" }
'

Use any non-digit(s) you like as the column number separator (eg comma or space).

Answer 3

ls -l | nawk -v r="3,5" 'BEGIN{split(r,a,",")}{for(i in a)printf $a[i]" ";print "\n"}'

Now you can simply change your r variable in shell script and pass it on. or you can configure it in your shell script and use r=$your_list_var

What ever fields numbers are present in $your_list_var will be printed by awk command. The example above print 3rd and 5th fields of ls -l output.