AWK script command line arguments and file input

Question

#!/usr/bin/awk -f

BEGIN{
    print ARGV[1]
}
{
    print $1, $3
}
END{
    print "Done"
}

I need to have both command-line arguments and file as input. I have tried the following and got the error shown:

cat users.txt |./temp.awk 3
3
awk: ./temp.awk:4: fatal: cannot open file `3' for reading (No such file or directory)

The command-line argument is shown but i cannot seem to find a way to read the file.

Thanks.

awk is expecting a filename instead of 3. If you need to pass an argument you can use v=3 instead and drop just report the value. — karakfa
– karakfa, Commented May 12, 2020 at 20:10
@karakfa Can this be done without using v = 3? Thanks for your response. — user10600161
– user10600161, Commented May 12, 2020 at 20:13
No, otherwise awk is going to expect a filename. Only the x=y type is treated as variable decleration. — karakfa
– karakfa, Commented May 12, 2020 at 20:15

Community · Accepted Answer · 2020-06-20 09:12:55Z

2

In this case, you may set ARGV[1] or ARGC inside the BEGIN block:

BEGIN {
    print ARGV[1]
    # Empty ARGV[1] so that it is not treated as a filename
    ARGV[1]=""
}
{
    print $1, $3
}
END {
    print "Done"
}

man 1p awk:

ARGC The number of elements in the ARGV array.

ARGV An array of command line arguments, excluding options and the program argument, numbered from zero to ARGC−1.

The arguments in ARGV can be modified or added to; ARGC can be altered. As each input file ends, awk shall treat the next non-null element of ARGV, up to the current value of ARGC−1, inclusive, as the name of the next input file. Thus, setting an element of ARGV to null means that it shall not be treated as an input file. The name '−' indicates the standard input. If an argument matches the format of an assignment operand, this argument shall be treated as an assignment rather than a file argument.

edited Jun 20, 2020 at 9:12

CommunityBot

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answered May 12, 2020 at 23:50

user13529681

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