what does the field separator in awk do here?

Question

In this context, how does the specified field separator work?

awk -F\' '{print "conn kill "$2"\nrepair mailbox "$2" repair=1"}'

Answer 1

AWK processes a file line by line. And each line is separated into fields, that you can then access with the dollar variables $1...$9 ($0 is the whole line, IIRC). By default, the line is split into fields by using separating on whitespace, but you can specify on which character to split by using the -F command line option or the FS variable.

So in your case, the field separator is set to a single quote ('). An input line like foo'bar'baz will thus set $1 == "foo", $2 == "bar" and $3 == "baz".

Answer 2

-F\' is using the single quote ' as the field separator.

Also the ' is being escaped by preceding it with a \ so that awk does not think of the ' as the beginning of the action part.

Alternatively you can enclose the ' in double quotes:

$ echo "foo'bar'baz" | awk -F\' '{print $1}'
foo
$ echo "foo'bar'baz" | awk -F"'" '{print $1}'
foo