grep the last string in a file

[Vijaya Kumar_3]

I have the following file.

/tmp/portslist

*.22
*.53
*.80
*.443
*.22132
*.21112
*.22124
*.22059
*.49316
*.22023
*.22015
*.22056
*.22091
*.22133
*.22057
127.0.0.1.49181
*.22105
*.22011
*.22090
*.2121
*.22063
*.33505
*.22119
*.22092
*.22131
*.22024
*.22077
*.22106
*.22136
*.22107
127.0.0.1.50290
*.34543
127.0.0.1.51291


As you can see, the last pattern after the . (dot) is the port number. How can I just get only the port number from this file...

I want an output like this.

22
53
80
443
22132
21112 etc

Thanks in advance. I will assign points.

Regards
Vijay Chinnasamy

[R.K. #]

Hello Vijay,

You can try this:

# cat /tmp/portslist | cut -d. -f2 > /tmp/ports

Regds..

[Vijaya Kumar_3]

Thx for the reply.

The command you gave will give the second field after the dot. This will not work in case of the pattern 127.0.0.1.49181

I am looking for the last field after the dot, that is only the port number from this file...


Regards
Vijay Chinnasamy

[R.K. # · Accepted solution]

Hi Again..

Sorry for that..
Try this one:

# cat portslists | awk 'BEGIN {RS="\n";FS="."};{print $NF}'

[Patrick Wallek]

No need to use cat and pipe the file into awk.

The above can be simplified to:

awk -F . '{print $NF}' /dir/filename

[Hein van den Heuvel]

If for some reason using "." as field separator does not work, or if you have processing for which PERL is more suitable, then you can use something like:

$ perl -lne 'print $1 if /\.(\d+)$/' file

That is a regular expression which looks for a period (escaped with \ ), followed by a number of digits (\d+) , remembered as $1 through those parens, and anchered at the end of the line with the $


The -l give a free new-line for each print (not needed whne processing furher) and he the -n tells perl to loop over an input file Not printing each line.

fwiw,
Hein.

[Suraj K Sankari]

Hi,

If your file is having only 2 field and field saperater is . then the command will be
#awk -F"." '{ print $NF }' outputfile

or

echo $filename | awk -F. '{print $NF}'

Suraj

[Steven Schweda]

sed -e 's/^.*\.\([^.]*$\)/\1/'

bash$ cat gt.txt
*.22133
*.22057
127.0.0.1.49181
*.22105

bash$ sed gt.txt -e 's/^.*\.\([^.]*$\)/\1/'
22133
22057
49181
22105


> grep the last string in a file

You mean _extract_ the last string in a file?
Who's using "grep"? Grep finds things. It
doesn't edit them. Don't choose a tool
until you understand what you wish to do with
it.

[Dennis Handly]

>Hein: If for some reason using "." as field separator does not work

It works fine. One char field separators are fixed. If more than one, it is an ERE.

If you really want to make awk sweat with an ERE, you can use: -F'\.'

[James R. Ferguson]

Hi Vijay:

Yet another way:

# perl -ne '@F=split /\./;print $F[@F-1]' file

Regards!

...JRF...