How to provide grep a file with ip addresses to look for in access.log
Situation
I have a file where each line has an IP address and I want to see if these Ip’s are found in access.log
File name: IpAddressess
Contents example :
192.168.0.1
192.168.0.2
192.168.1.5
etc etc
Now I want to scan access.log for these IP addresses contained in the file IpAddressess
Can I use the command grep for this and what would the command structure look like?
Thank you kindly for any assistance!
Yes, use grep -f. Worth adding the -F to that the . character in your patterns doesn’t get interpreted as ‘any’ character.
-f and -F is explained below
$ grep --help 2>&1|grep -i '^ -f'
-F, --fixed-strings PATTERNS are strings
-f, --file=FILE take PATTERNS from FILE
$
Example:
$ cat patterns
192.168.0.1
192.168.0.2
192.168.1.5
$ cat myaccesslog
hello 192.168.0.1
world ! 192.168.0.2
foobar 192.168.0x1
$ grep -f patterns myaccesslog
hello 192.168.0.1
world ! 192.168.0.2
foobar 192.168.0x1
$ grep -Ff patterns myaccesslog
hello 192.168.0.1
world ! 192.168.0.2
$
You are looking for the -f option, described in man grep on my Arch Linux system as:
-f FILE, --file=FILE
Obtain patterns from FILE, one per line. If this option is
used multiple times or is combined with the -e (--regexp)
option, search for all patterns given. The empty file contains
zero patterns, and therefore matches nothing.
However, since grep works with regular expressions and . in regular expressions means "any character", you will also want the -F option, so that 1.2.3 doesn’t match things like 10293:
-F, --fixed-strings
Interpret PATTERNS as fixed strings, not regular expressions.
Putting the two together, the command you’re looking for is:
grep -Ff IpAddressess access.log