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Home: Perl Programming Help: Intermediate: Replacing exact match of IP from list of files

saurabhsharma Novice Jan 19, 2012, 3:36 AM Post #1 of 8 (848 views) Replacing exact match of IP from list of files Can't Post Hi, I have number of files containing IP address list. I want to replace exact match of IP with some other value. e.g. One of IP list file contains 1. 10.23.23.241 url=jdbc:oracle:thin:@//110.235.345.21//10.235.345.21.abc.com 2. 10.23.23.241 10build 10build23.abc.com 3. 10.23.23.241 3s10build4 s10build2.iabc.com 4. 10.23.23.241 s10build s10build2.xyz.com 5. 10.23.23.241 10.235.345.214 10.235.345.21:1521build.www.com 6. VIPADDRESS=10.235.345.21 10.235.345.21:1521build. i ONLY want to change exact match of (10.235.345.21) to (10.10.10.10) means first line in the file 10.23.23.241 url=jdbc:oracle:thin:@//110.235.345.21//10.235.345.21.abc.com MUST be replaces as 10.23.23.241 url=jdbc:oracle:thin:@//110.235.345.21//10.10.10.10.abc.com In otherwords value "110.235.345.21" value must NOT be changed as this is not the exact match as it contains digit "1" before "10.235.345.21" likewise line number 5 5. 10.23.23.241 10.235.345.214 10.235.345.21:1521build.www.com must be changed to 10.23.23.241 10.235.345.214 10.10.10.10:1521build.www.com , again value in this line "10.235.345.214" must NOT be changed as it contains digit "4" in at the last position. So the idea is to replace the exact match of value 10.235.345.21 provided there should be no digit preceeding it or present as the last character. I have written shell script ehich is using perl command as OLD_VAL= 10.235.345.21 NEW_VAL= 10.10.10.10 /usr/bin/perl -p -i -e "s/([^\d])$OLD_VAL([^\d])/\1$NEW_VAL\2/" $FILENAME where FILENAME is the name of the file ro be modified as i don't want to open the file and process each line individually (even though the command is doing so internally) The error i get is that it replaces the values which starts with "H", means it replaces the file into 1. 10.23.23.241 url=jdbc:oracle:thin:@//110.235.345.21/H.10.10.10.abc.com 2. 10.23.23.241 10build 10build23.abc.com 3. 10.23.23.241 3s10build4 s10build2.iabc.com 4. 10.23.23.241 s10build s10build2.xyz.com 5. 10.23.23.241 10.235.345.214H.10.10.10:1521build.www.com 6. VIPADDRESSH.10.10.10H10.10.10:1521build. Like wise if the replacing IP starts with 11.X.X.X it replaces the first character with “I” and eats up first character. please help Saurabh (This post was edited by saurabhsharma on Jan 19, 2012, 4:53 AM)

rovf Veteran Jan 19, 2012, 5:58 AM Post #2 of 8 (842 views) Re: [saurabhsharma] Replacing exact match of IP from list of files [In reply to] Can't Post What characters in front of the first digit do "delimit" those IP addresses you want to replace? Anything non-numeric? Any special character? Only a certain set of special characters? You need to define this, before you can solve this problem, because you want to search for a pattern, which are NOT preceded by another pattern. After having done this specification task, look at perldoc perlre You will find there, for example: \D ... matches a non-digit \b ... matches a word boundary [^.....] ... matches any character which is not in the set \W ... matches a non-word character (?<=pattern) ... zero-width look behind and many more.

saurabhsharma Novice Jan 20, 2012, 12:10 AM Post #3 of 8 (838 views) Re: [rovf] Replacing exact match of IP from list of files [In reply to] Can't Post Hi rovf, The pattern i am looking for is : if preceded or end by any numeric digit the string should not be replaced that is why i have used ([^\d])$OLD([^\d]) in the search pattern, but what it does is that once it finds the pattern it is replacing it with first character as Alphabetical character and garbling the replaced pattern as i quoted in the question. 10.23.23.241 url=jdbc:oracle:thin:@//110.235.345.21/H.10.10.10.abc.com I am unable to figure out why, but when i replace “to be replaced” string 10.10.10.10 to start with any character it is working fine i.e if i change 10.10.10.10 to let’s say A10.10.10.10 the replacement is working fine and it would replace the above mentioned string to 10.23.23.241 url=jdbc:oracle:thin:@//110.235.345.21//A10.10.10.10.abc.com Can you please explain why ?

saurabhsharma Novice Jan 20, 2012, 12:56 AM Post #4 of 8 (837 views) Re: [saurabhsharma] Replacing exact match of IP from list of files [In reply to] Can't Post i rovf, I figured out the problem, it was the problem with the perl command i was giving, i must have replace \1 and \2 in my substitution command to \${1} and \${2} old command was /usr/bin/perl -p -i -e "s/([^\d])$OLD_VAL([^\d])/\1$NEW_VAL\2/" $FILENAME the correct one is /usr/bin/perl -p -i -e "s/([^\d])$OLD_VAL([^\d])/\${1}$NEW_VAL\${2}/" $FILENAME Now its working like charm Cheers, Saurabh

rovf Veteran Jan 20, 2012, 2:11 AM Post #5 of 8 (833 views) Re: [saurabhsharma] Replacing exact match of IP from list of files [In reply to] Can't Post BTW, you can write [^\d] in a more compact way as \D.

saurabhsharma Novice Jan 22, 2012, 9:05 PM Post #6 of 8 (823 views) Re: [rovf] Replacing exact match of IP from list of files [In reply to] Can't Post Yes But using ([\D]*) is better

rovf Veteran Jan 23, 2012, 1:52 AM Post #7 of 8 (813 views) Re: [saurabhsharma] Replacing exact match of IP from list of files [In reply to] Can't Post In your case, no. Aside from the fact that the brackets are unnecessary ([\D] can be simply written as \D), the asterisk doesn't make sense. \D* means: "zero or no non-digits". Hence it matches ANY zero-length part of your string - certainly not what you have in mind. You could write \D+, but since you don't collect the non-digits, this doesn't bring any advantage over just writing \D. You should, however, conisder the case, whether the pattern you are looking for, could also appear at the *start* of the string. In this case, you would need something like (^|\D).

saurabhsharma Novice Jan 23, 2012, 5:33 AM Post #8 of 8 (808 views) Re: [rovf] Replacing exact match of IP from list of files [In reply to] Can't Post Yes i had used ([^\d]|^) instead, (^|\D) works the same way and look cleaner too. Thanks

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