R3gEx

Grep for IP Addresses:
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Only the IP:
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grep -o '[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}' file.txt

Only one IP and ONLY if it is at the beginning of the line:
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grep '^[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}$' file.txt

Any IP and the rest of the line it is one:
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grep '[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}' file.txt

Convert sequential lines of text to space delimitated list:
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perl -pe 's/\s*$/ /' filename.txt

Sort IP's properly:
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sort -t . -k 1,1n -k 2,2n -k 3,3n -k 4,4n

Display only unique IP's from above sort command:
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| uniq

Remove all white space from left to first word:
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cat | sed -e 's/^[ \t]*//'