avoid awk conditionals on certain fields

Question

I have "|" delimited file, with fields that represent:

firstname|secondname|Kernel|Version|Year

For example:

Linus|Torvald|VMLINUZ||1994
Jochen|Liedtke|L4|||
Apple||Darwin||2000

I want "\t" delimited results, with few conditionals. If any column is empty, it'll substitute with "-", but it gets complex in few cases, where any of first or second name is empty. I don't want it to happen.

Simply, concatenate first & second name, but if any of these columns empty, don't replace with "-" otherwise this condition applies on other empty fields.

I wrote following awk script, but it replaces empty first or second name with "-" too.

BEGIN {
FS="|";
OFS="\t"
}
{ for (i = 1; i <= NF; ++i) sub(/^$/, "-", $i) }
{
print $5, $4, $2" "$1
}

It gives this output:

1994    -   Torvald Linus
-   -   Liedtke Jochen
2000    -   - Apple

so the last line should be

2000    -   Apple

Final Output

1994    -   Torvald Linus
-   -   Liedtke Jochen
2000    -   Apple

Ed Morton · Accepted Answer · 2021-07-06 18:11:33Z

3

This is probably what you're trying to do:

$ cat tst.awk
BEGIN { FS="|"; OFS="\t" }
{
    for (i=3; i<=NF; i++) {
        if ($i == "") {
            $i = "-"
        }
    }
    print $5, $4, ($2=="" ? "" : $2 " ") $1
}

$ awk -f tst.awk file
1994    -       Torvald Linus
-       -       Liedtke Jochen
2000    -       Apple

edited Jul 6, 2021 at 18:11

answered Jul 6, 2021 at 18:05

Ed Morton

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