Extracting IP from IP.port
I’ve done a lot of digging but haven’t found an answer to my problem.
Currently, I have the following command:
netstat | grep telnet | grep ESTABLISHED | awk 'NR==1{ print $5}'
Which returns something like this:
192.168.15.73.64759
From this, I want to get just the IP without the port. So,
192.168.15.73
The system I’m doing this on runs an embedded Unix variant (QNX) and does not support -o as an option to grep. The system supports sed which is likely the best route, but I’m unfamiliar with that application.
Can anyone tell me what I could add to get the output I’m looking for?
You could use cut or sed:
echo 192.168.15.73.64759 | cut -d '.' -f 1-4
echo 192.168.15.73.64759 | sed -E 's,.[0-9]+$,,'
Or awk:
echo 192.168.15.73.64759 | awk -F '.' '{print $1"."$2"."$3"."$4}'
Use string substitution:
$ IP=192.168.15.73.64759
$ echo ${IP%.*}
192.168.15.73
IP=$(netstat | grep telnet | grep ESTABLISHED | awk 'NR==1{ print $5}')
echo ${IP%.*}
Having just learned about ss:
ss -n -o state established '( dport = :telnet or sport = :ssh )' |
awk 'NR==2 { print substr($5, 1, index($5, ":")-1) }'
I use NR==2 to skip past the header and grab only the first line of output, to corresponding with your netstat/grep behavior. The rest of the awk code prints $5, but starting from the first character and only going until the index where “:” is found, minus one.
If the system is missing ss, then you can use sed:
echo 192.168.15.73.64759 | sed 's/.[0-9]*$//'
netstat | grep telnet | grep ESTABLISHED | awk 'NR==1{ print $5}' | sed 's/.[0-9]*$//'
This replaces “period followed by zero or more digits followed by the end of the line” with “nothing”.
netstat | grep telnet | grep ESTABLISHED | awk 'NR==1{ print $5}' |grep -Po "b(?:d{1,3}.){3}d{1,3}b"
You can also do that using grep -E
in="192.168.15.73.64759"
echo $in | grep -Eo "([[:digit:]]{1,3}.){4}" | grep -Po "(.*)(?=.$)"
~#: 192.168.15.73
the -E allows extended regex, and -P for Perl compatible to include the last dot in the pattern but excluding it from the output
Applying a single awk command to the output of netstat would be enough to capture any line that contains the sub-strings ESTABLISHED and telnet and then output a trimmed 5th field.
netstat | awk '/ESTABLISHED/ && /telnet/ { sub(/.[^.]+$/,"",$5); print $5 }'
If you need only the first result, change print $5 to print $5; exit in the awk code, or pass it through head -n 1.