How can I use awk to join various fields, given that I don't know how many of them I have? For example, given the input string
aaa/bbb/ccc/ddd/eee
I use -F'/'
as delimiter, do some manipulation on aaa
, bbb
, ccc
, ddd
, eee
(altering, removing...) and I want to join it back to print something line
AAA/bbb/ddd/e
Thanks
... given that I don't know how many of them I have?
Ah, but you do know how many you have. Or you will soon, if you keep reading :-)
Before giving you a record to process, awk
will set the NF
variable to the number of fields in that record, and you can use for
loops to process them (comments aren't part of the script, I've just put them there to explain):
$ echo pax/is/a/love/god | awk -F/ '{
gsub (/god/,"dog",$5); # pax,is,a,love,dog
$4 = ""; # pax,is,a,,dog
$6 = $5; # pax,is,a,,dog,dog
$5 = "rabid"; # pax,is,a,,rabid,dog
printf $1; # output "pax"
for (i = 2; i <= NF; i++) { # output ".<field>"
if ($i != "") { # but only for non-blank fields (skip $4)
printf "."$i;
}
}
printf "\n"; # finish line
}'
pax.is.a.rabid.dog
This shows manipulation of the values, as well as insertion and deletion.
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