How do you check if a file exists within awk? [-d 'filename'] failing

You could use

system(command)
    Execute the operating-system command command and then
    return to the awk program. Return command’s exit status.

e.g.:

awk -F: '{if(system("[ ! -d " $6 " ]") == 0) {print $1 " " $3 " " $7}}' /etc/passwd

I don't think that [ -d ] is an awk thing, that's a shell thing. I would just do it this way instead:

awk -F: '{ print $1,$3,$7}' /etc/passwd | 
    while read name uid shell; do 
        [ -d "/home/$name" ] || echo "$name $uid $shell"; 
    done

Of course, as very correctly pointed out by @Janis, you can do the whole thing in the shell:

while IFS=: read  name x uid x x x shell rest; do
     [ -d "/home/$name" ] || echo "$name $uid $shell" 
done < /etc/passwd

You can use getline:

awk 'BEGIN {print getline < "file" < 0 ? "not exists" : "exists"}'

Related