sed / awk: how to delete lines that DON'T match a pattern?

[negativ]

I have a file that looks like this:

192.168.10.123 blah blah text
192.168.10.123
192.168.10.10 more text
192.168.10.10
192.168.10.12
192.168.10.9 yet more text

How can I delete the lines that are only IP addresses, and leave the lines that are IPs with the text after them?

[trent.josephsen]

I have a file that looks like this:

192.168.10.123 blah blah text
192.168.10.123
192.168.10.10 more text
192.168.10.10
192.168.10.12
192.168.10.9 yet more text

How can I delete the lines that are only IP addresses, and leave the lines that are IPs with the text after them?

$ grep -v '^[\.[:digit:]]*$' <myfile

That matches all lines that contain nothing but a string of dots and digits. Might not be 100 percent effective. For that matter, you could

$ grep ' ' <myfile

which would pick out only lines with no spaces in them (the -v flag inverts the test).

[DaithiF]

Hi,
just to show some sed equivalents:

print lines that don't match a pattern, or delete lines that do ... both achieving the same result

$ sed -n '/[0-9]$/!p' testfile
192.168.10.123 blah blah text
192.168.10.10 more text
192.168.10.9 yet more text

$ sed '/[0-9]$/d' testfile
192.168.10.123 blah blah text
192.168.10.10 more text
192.168.10.9 yet more text

[ghostdog74]

I have a file that looks like this:

192.168.10.123 blah blah text
192.168.10.123
192.168.10.10 more text
192.168.10.10
192.168.10.12
192.168.10.9 yet more text

How can I delete the lines that are only IP addresses, and leave the lines that are IPs with the text after them?

$ grep -P -v '^\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3}$' file
192.168.10.123 blah blah text
192.168.10.10 more text
192.168.10.9 yet more text

[ghostdog74]

Hi,
just to show some sed equivalents:

print lines that don't match a pattern, or delete lines that do ... both achieving the same result

$ sed -n '/[0-9]$/!p' testfile
192.168.10.123 blah blah text
192.168.10.10 more text
192.168.10.9 yet more text

$ sed '/[0-9]$/d' testfile
192.168.10.123 blah blah text
192.168.10.10 more text
192.168.10.9 yet more text

that is, provided OP's data always have an IP address as its first field.