Node:File Checking, Next:Ignoring Assigns, Previous:Rewind Function, Up:Data File Management

Checking for Readable Data Files

Normally, if you give awk a data file that isn't readable, it stops with a fatal error. There are times when you might want to just ignore such files and keep going. You can do this by prepending the following program to your awk program:

# readable.awk --- library file to skip over unreadable files
BEGIN {
    for (i = 1; i < ARGC; i++) {
        if (ARGV[i] ~ /^[A-Za-z_][A-Za-z0-9_]*=.*/ \
            || ARGV[i] == "-")
            continue    # assignment or standard input
        else if ((getline junk < ARGV[i]) < 0) # unreadable
            delete ARGV[i]
        else
            close(ARGV[i])
    }
}

In gawk, the getline won't be fatal (unless --posix is in force). Removing the element from ARGV with delete skips the file (since it's no longer in the list).