UNIX for Dummies Questions & Answers

Hi,
i can print 2nd, 4th and 6th columns in a file using the shell command:

awk -F "|" '{print $2 $4 $6}' file1.txt

Now, the position and number of columns can be variable and from a variable POSLIST
So let's say
POSLIST='$2 $4 $6'

when i use the command:

a)
awk -F "|" '{print $POSLIST}' file1.txt

it throws the error:
awk: Field $() is not correct.

b)
awk -v VAR=$POSLIST -F "|" '{print $POSLIST}' file1.txt
or
awk -v VAR="'"$POSLIST"'" -F "|" '{print $POSLIST}' file1.txt

error:
awk: Cannot find or open file $2.

c)
awk -F "|" '{print `echo $POSLIST`}' file1.txt

error:
The error context is
{print >>> ` <<<
awk: The statement cannot be correctly parsed.


None of the above syntax worked.
How to pass variable containing column positions to the print statement?

Thanks,
-srinivas yelamanchili

Try in this way ..

Code:

$ cat infile
1|2|3|4|5|6|7
$
$ a='$2 $3 $4'
$
$ echo $a
$2 $3 $4
$
$ echo "awk -F\| '{print $a}' infile" | sh
234
$

Hi ysrini,

Other way:

Code:

$ awk -F\| -v vara="$a" '{ gsub( /\$/, "", vara ); split( vara, arr, /\s+/ ); for ( i in arr ) { print $arr[i] } }' infile

Regards,
Birei