How to use multiple delimiters in awk?

Question

I want to split up a variable using awk by a colon, but only the last variable.

From this input:

 ACCEPT     tcp  --  0.0.0.0/0     0.0.0.0/0     tcp dpt:22

I want the following output:

 protocol=tcp source=0.0.0.0/0 destination=0.0.0.0/0 port=22

This is my awk command now:

 awk '/^ACCEPT/ {print "protocol=",$2, "source=",$4,"destination=",$5,"port=",$7}"

Which produces:

protocol=tcp source=0.0.0.0/0 destination=0.0.0.0/0 port=dpt:22

But I want to get 22 out of $7 and not dpt:22

I've tried using awk's field separator, but I can figure out how to make it only apply to a single variable

Answer 1

Just tweak FS to include the :

$ echo 'ACCEPT     tcp  --  0.0.0.0/0     0.0.0.0/0     tcp dpt:22' |
     awk '/^ACCEPT/{printf("protocol=%s source=%s destination=%s port=%s\n", $2,$4,$5,$8)}
     ' FS='[ :]*'
protocol=tcp source=0.0.0.0/0 destination=0.0.0.0/0 port=22

You might need to include tabs, and do FS='[ :\t]*'

Answer 2

You can use a regex to define a custom field separators in awk.

some_command | awk -F '[[:blank:]:]+' '/^ACCEPT/{
   printf "protocol=%s source=%s destination=%s port=%s\n", $2, $4, $5, $NF}'

protocol=tcp source=0.0.0.0/0 destination=0.0.0.0/0 port=22

-F '[[:blank:]:]+' sets input field separator as one of white-space or colon.

Answer 3

slight modification in your awk command

$ awk '/^ACCEPT/ {gsub(/[^0-9]/,"",$7); print "protocol="$2, "source="$4,"destination="$5,"port="$7}' file
protocol=tcp source=0.0.0.0/0 destination=0.0.0.0/0 port=22

gsub(/[^0-9]/,"",$7); will nullify all non-digit characters in $7

Answer 4

Use the following awk approach:

awk '{ printf "protocol=%s source=%s destination=%s port=%s\n",$2,$4,$5,substr($7,5) }' file

---

But if the last field has dynamic prefix length you may apply gsub() function to remove non-digit characters:

awk '{ gsub(/^[^0-9]+/,"",$7); printf "protocol=%s source=%s destination=%s port=%s\n",$2,$4,$5,$7 }' file