[SOLVED] how to compare $var with content of file

Basher52 · 05-20-2011, 02:45 AM

This is a simple thing but I just can't get it to work.

I got a file with a list of subnets like this:

10.50
10.51
10.62
10.121

...then I cnf=`ifconfig` thus giving me the config of the NICs

...after that I want to compare the $cnf to see if the value of it is
listed in the file and if it is do things.
There might also be something better to use then the 'ifconfig' but it worked so I just stuck to it

First I just had one subnet but now it's starting to grow and I wanna make a list instead of having them all listed in the if-statement.

I know this gotta be possible since it's Linux but whatever I do won't work

catkin · 05-20-2011, 02:54 AM

Please post your script and show how it does not work

Basher52 · 05-20-2011, 03:00 AM

well I can't post it since I haven't really save it

I just "test" it at the command prompt before I do.
I can post this at least:

Code:

if [ `ifconfig | grep -ci 10.200` != 0 ]; then
        /bin/eject /dev/cdrom ; reboot -f
elif [ `ifconfig | grep -ci 10.70` != 0 ]; then
        /bin/eject /dev/cdrom ; reboot -x
else echo Unknown network. Please tell me what to do...

and now each of the if statement will now have more then just one, so far we're up to 12 of subnets and it's still growing therefore I wanna put them in a file.

colucix · 05-20-2011, 03:11 AM

If you have a list of subnets in a file you can reverse the logic and see if a specific subnet (from the ifconfig command) is listed into the file itself. Example with a while read loop taking input from the output of ifconfig parsed with awk:

Code:

while read subnet
do
  if grep -qw $subnet file
  then
    echo $subnet
  fi
done < <(/sbin/ifconfig | awk '/inet addr:/ && ! /127.0.0.1/{sub(/inet addr:[0-9]+\.[0-9]+\./,""); print $1}')

where file in the grep command is your saved list. The awk line excludes the lo address from the search and extract the subnet (two last octets of the IP address). Hope this helps.

Basher52 · 05-20-2011, 03:52 AM

thx that was fast

wish I was familiar with 'awk' as you are. Love that command but I can't handle it

colucix · 05-20-2011, 04:20 AM

Code:

/sbin/ifconfig | awk '
/inet addr:/ && ! /127.0.0.1/ {
  sub(/inet addr:[0-9]+\.[0-9]+\./,"")
  print $1
}'

Actually not so complicated: you have two expressions to match your input line concatenated by the logical AND operator &&. It matches the regular expression /inet addr:/ and doesn't match (that is excludes, see the negation operator !) the loopback address /127.0.0.1/.

The rules is quite simple: the sub fuction substitutes the text matched by /inet addr:[0-9]+\.[0-9]+\./ with the null string. In other words it removes the string

Code:

inet addr:XXX.YYY.

from the input, leaving only the last two octets of the IP address into the first field. Hope it's a bit more clear.

If you want to learn more about awk I suggest to read the following:
http://www.gnu.org/software/gawk/manual/ the official GNU awk guide
http://www.grymoire.com/Unix/Awk.html the awk tutorial at grymoire's site

Basher52 · 05-20-2011, 04:39 AM

Doesn't seem to 'want' this tho:

Code:

while read subnet

 do if grep -qw $subnet ./subnet.adm; then
        /bin/eject /dev/cdrom ; reboot -x
 elif if grep -qw $subnet ./subnet.utb; then
        /bin/eject /dev/cdrom ; reboot -f
 else echo Unknown subnet: $subnet. Script canceled and eagerly awaits instructions...
fi

done < <(/sbin/ifconfig | awk '/inet addr:/ && ! /127.0.0.1/{sub(/inet addr:[0-9]+\.[0-9]+\./,""); print $1}')

I get a "syntax error near unexpected token 'done'"
Is there no possibility to have this in a if-else statement?

I gotta read up on 'awk' and understand that command

Basher52 · 05-20-2011, 04:53 AM

'... elif if...'

lol

Basher52 · 05-20-2011, 05:11 AM

Code:

while read subnet

 do if grep -qw $subnet ./subnet.adm; then
        /bin/eject /dev/cdrom ; reboot -x
 elif grep -qw $subnet ./subnet.utb; then
        /bin/eject /dev/cdrom ; reboot -f
 else echo Unknown subnet: $subnet. Script canceled and eagerly awaits instructions...
fi

done < <(/sbin/ifconfig | awk '/inet addr:/ && ! /127.0.0.1/{sub(/inet addr:[0-9]+\.[0-9]+\./,""); print $1}')

I removed the error I created but then I get error at another place:

Code:

/bin/ftl: line 19: syntax error near unexpected token `<´
/bin/ftl: line 19: `  done < <(/sbin/ifconfig | awk ´/inet addr:/ && ! /127.0.0.1/{sub(/inet addr:[0-9]+\.[0-9]+\./,""); print $1}´)´

These lines are typed manually so I might have written some stuff wrong

crts · 05-20-2011, 05:37 AM

Hi,

I ran your script and did not get a syntax error. Which shell are you using?

Basher52 · 05-20-2011, 05:55 AM

It's at work for a BootCD from Novell ZENworks 10.3.3 using SUSE

UPDATE: Linux (none) 2.6.32.19-0.3-default

crts · 05-20-2011, 06:07 AM

Quote:

Originally Posted by Basher52

It's at work for a BootCD from Novell ZENworks 10.3.3 using SUSE

UPDATE: Linux (none) 2.6.32.19-0.3-default

No, what I meant are you using bash, csh or something else? AFAIK not every shell does support process substitution.

Basher52 · 05-20-2011, 06:09 AM

crts · 05-20-2011, 06:17 AM

Quote:

Originally Posted by Basher52

bash

Are you sure? And did you post the complete script?

I copy+pasted your script and ran it twice with different sha-bangs.

Code:

#!/bin/bash
while read subnet
...
done < <(/sbin/ifconfig | awk '/inet addr:/ && ! /127.0.0.1/{sub(/inet addr:[0-9]+\.[0-9]+\./,""); print $1}')

This did not return a syntax error.

This, however,

Code:

#!/bin/sh
while read subnet
...
done < <(/sbin/ifconfig | awk '/inet addr:/ && ! /127.0.0.1/{sub(/inet addr:[0-9]+\.[0-9]+\./,""); print $1}')

returned the error

Code:

$ ./sh.scr
./sh.scr: 12: Syntax error: redirection unexpected

So can you post the complete script, including the sha-bang?

Basher52 · 05-20-2011, 06:25 AM

This script doesn't have a sha-bang since it's just a subscript called from another one that's inside the 'initrd' when it boots up.

Maybe I can try to use that #!/bin/bash in THIS script and see what happens.

I tried that and now no error other then that the subnet files was in the wrong place

Gonna change that and test again.

btw, what's the difference between bash and csh?
http://www.unix.com/shell-programmin...n-bash-sh.html

thx for the help so far, hadn't much knowledge about the difference between cs, bash, csh and tsch