Grep Command

grep -ir word *

Search all files for keyword "word" in current folder and sub-folders

grep -ir -e word1 -e word2 *

Search all files for keyword "word1" or "word2" in current folder and sub-folders

grep -v word

Search all files exclude keyword "word" in current folder and sub-folders

cat file | grep -o '[^:]*$'

cat the file and using grep to find the last field (cut ":" )

grep -vFxf /tmp/exclude /tmp/all

Compare two files the to show the context wihtout exclude list, such as:

/tmp/exclude	/tmp/all

111			111
222			222
333			333
			444
			555

The result only show :
444
555

grep -Fxf /tmp/exclude /tmp/all

Compare two files the to show the match context, such as:

/tmp/file1	/tmp/file2

111			111
222			222
333			333
			444
			555

The result only show :
111
222
333