GREP
grep command is an abbreviation Globally search a Regular Expression and Print, showing globally matching and regular print. grep command, including the expansion of related egrep and fgrep, egrep which supports more regular matches, fgrep only match characters and does not support regular expressions.
grep [the OPTIONS] [-e the PATTERN | -f FILE] [FILE ...] the OPTIONS rows -n match also showed up -A 3 to 3 lines after the match also showed up 3 industry before -B 3 matches display out -o only a portion of the output matching -v reverse match -f specified files need to match the root @ wdev02: / usr / local / CAT # 1.txt the shell 123 345 the root @ wdev02: / usr / local / CAT # the shell 2.txt ABC BCD 123 haha Hehe 23456 Hello ABCD the root @ wdev02: / usr / local / # grep -n. 3 2.txt the shell . 3: 123 . 6: 23456 the root @ wdev02: / usr / local / # grep -w the shell - 1.txt 2.txt -f n- . 3: 123