[SOLVED] Find Text After String Search in Text File

redir · 08-02-2011, 02:32 PM

Hello, spent too much time searching this and I know it's as simple as pie. I have a file called Regions.ini that looks like this:

Code:

[Granite]
RegionUUID = 54ab7cd2-0e70-49b7-8020-8dbeb84c08d0
Location = 9991,10007
InternalAddress = 0.0.0.0
InternalPort = 9001
AllowAlternatePorts = False
ExternalHostName = 71.171.21.9

[Syenite]
RegionUUID = 8fc56fdd-0afd-4074-9432-0ae8f42b799f
Location = 9992,10007
InternalAddress = 0.0.0.0
InternalPort = 9000
AllowAlternatePorts = False
ExternalHostName = 71.171.21.9

What I need to do is find out what the IP address is after "ExternalHostName ="

Thats it. Pretty simple huh.

After that I will need to compare that IP to whatismyip and if it's different then replace it but that is easy to do with sed. I just can't figure this simple hurdle out.

Thanks.

crts · 08-02-2011, 02:51 PM

Hi,

try this to get the IPs

Code:

awk '{ if ($1 == "ExternalHostName") { print $3 } }' file

redir · 08-02-2011, 03:23 PM

Quote:

Originally Posted by crts

Hi,

try this to get the IPs

Code:

awk '{ if ($1 == "ExternalHostName") { print $3 } }' file

Yes thanks a lot! here is the output:

71.171.21.9
71.171.21.9

How do I get it to just print the IP once?

sycamorex · 08-02-2011, 03:33 PM

You can use 'uniq' if you want to get rid of duplicate lines.

sycamorex · 08-02-2011, 03:41 PM

A sed version of the same would be:

Code:

sed -n '/ExternalHostName = / s///p' file | uniq

redir · 08-02-2011, 03:42 PM

Perfect! You guys are great.

crts would you be so kind as to explain how that command works? I'd like to learn something other then cut and paste

redir · 08-02-2011, 03:43 PM

Ah the sed statement works also thank you.

crts · 08-02-2011, 03:44 PM

Quote:

Originally Posted by redir

Yes thanks a lot! here is the output:

71.171.21.9
71.171.21.9

How do I get it to just print the IP once?

That depends. Are there many differenr IP that you need to extract? Then use the aforementioned 'uniq'. If this is the only IP-pair in your file then you could simply 'exit' the awk script after the first encounter:

Code:

awk '{ if ($1 == "ExternalHostName") { print $3;exit } }' file

sycamorex · 08-02-2011, 03:47 PM

Knowing that it's always going to be line 7 would make 'uniq' unnecessary:

Code:

sed -n '7s/ExternalHostName = //p' file

sycamorex · 08-02-2011, 03:50 PM

As crts mentioned there are a lot of factors that depend on your input file(s). Is the file you're working with exactly like the one you posted or is it just a sample of a longer file with the same/different IP addresses?

Here's a great tutorial on both awk and sed:
http://www.grymoire.com/Unix/

crts · 08-02-2011, 03:52 PM

Quote:

Originally Posted by redir

Perfect! You guys are great.

crts would you be so kind as to explain how that command works? I'd like to learn something other then cut and paste

Ok, let's break it down.

Code:

awk '{ if (condition) { commands } }' file

The commands inside '{}' will only be executed if (condition) is true.
In out case the condition is:

Code:

$1 == "ExternalHostName"

The $1 refers in awk to the first column. It is not to be confused with bash's positional parameters. So our condition checks every line of the input, if the first word is ExternalHostName. If that is true then

Code:

print $3

is executed. This instructs awk to print the third word of this line.

For further reference you might want to read:
http://www.gnu.org/software/gawk/manual/gawk.html

redir · 08-02-2011, 03:53 PM

Yeah that file is exactly like that and will never change. I have dynamic dns so when my ISP changes my IP address I need to open that file, change to the new IP then close it and restart the simulator program.

sycamorex · 08-02-2011, 03:57 PM

Quote:

Originally Posted by redir

Yeah that file is exactly like that and will never change. I have dynamic dns so when my ISP changes my IP address I need to open that file, change to the new IP then close it and restart the simulator program.

Yeah, in that case any solution that has been provided in this thread should work just fine. If you want to learn more about awk/sed, please have a look at the tutorial I linked to in one of my previous posts. It's very good.