Edit line a textfile using linux shell

Question

I need to change an IP-address in a text-file using linux-shell. How can I do that? Do you know a great source for regular expressions?

the textfile.txt contains sth like this:

# text text ffeefe 
Whatever text text ffeefe 
# text text ffeefe 
#
IPAddress : 192.168.200.40
#
# text text ffeefe
#
Whatever text text ffeefe 
# text text ffeefe

This is what I am looking for:

sed -i / find XXX.XXX.XXX.XXX / 192.168.200.41 / textfile.txt

The IP could be anything in that format XXX.XXX.XXX.XXX e.g. 192.168.200.40

it looks like you already have it, don't you? `sed -i 's/FIND/REPLACE/' file`. — fedorqui, Jun 19 '15 at 10:47
it is not clear if the ip is this 192.168.200.40 or 192.168.120.12 or something else. — frank schmidt, Jun 19 '15 at 10:51
Does it occur only once in the file? Does it occur after a specific content? Does it need to check if the line is commented or not? Provide more detail. — fedorqui, Jun 19 '15 at 10:51
Does it occur only once in the file? Yes. Does it occur after a specific content? no. new line. Does it need to check if the line is commented or not? yes. it has to check if the line is commented. — frank schmidt, Jun 19 '15 at 11:00
if only 1 ip in text, then checking is line commented is unneeded? — josifoski, Jun 19 '15 at 11:07

score 1 · Accepted Answer · edited Jun 19 '15 at 11:06

Although fedorqui is right with asking more information about occurring of IP after specific content, I'll provide (easy) solution for finding any IPv4 string.

The expression is:

[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+

using it in sed looks like this:

sed -i -r 's/[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+/newip/' file

On the other hand, if this is fixed "IPAddress : " before IP, then the OP should just use the IP they want.

score 0 · Answer 2 · answered Jun 19 '15 at 14:27

0

This will find line beginning with IPAddress : and change the digits to the new IP.

sed -i -r '/^IPAddress :/s/[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+/192.168.200.41/' textfile.txt

answered Jun 19 '15 at 14:27

Nathan Wilson

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Edit line a textfile using linux shell

2 Answers2