The Three Musketeers of Linux text Processing

Grep: Text Filtering tool, (GREP,EGREP,FGREP) Sed: Text Editing Tool, Awk: Text Report Generator

grep: Function Text Search tool to step through the target file matching checks according to user-specified ' mode, print matching lines

grep root/etc/passwd grep command options:

grep "$USER"/etc/passwd-v shows lines that are not matched by pattern-e show only the matched string

grep "$USER '/etc/passwd-i ignores character case-C statistics match to the number of rows-W match word

grep ' WhoAmI '/etc/passwd-n displays the matching line number-A # After a few lines-b# the first few lines-c# before and after # lines

Nmap Scan Tool nmap-sp-v 172.18.252.0/24 |grep-b1 up |grep scan |cut-d "f5 > 1.txt scan up IP address

NMAP-V-A IP address scan the open port of the machine

Ifconfig eth1 |grep "inet addr" |cut-d:-f2|cut-d ""-F1 Filter IP Address

DF |grep/dev/sd|tr-s '%|cut-d%-f5|sort-nr|head-1 view disk maximum usage

Regular Expressions: Another class of special characters and text characters written by the mode, indicating that the function of control or wildcard divided into two categories: basic regular Expression BRE extended regular expression ERE

Character matching:. Match a single arbitrary character

[] matches any single character within the specified range

[^] matches any single character outside the specified range

Number of matches: * matches the preceding character any time, including 0 position anchoring: ^ Meow at the beginning of the line

. * Match any character any time $ line end Meow

\? Matches the preceding character 0 or 1 times ^$ represents a blank line ^pattern$ used for pattern matching positive rows

\+ matches the preceding character at least once ^[[:space:]]*$ a blank line

\{n\} matches the preceding character n times \< or \b The first meow \> or \b The suffix meow, for the right side of the word pattern

\{m,n\} matches the preceding character at least m times, up to N times \<pattern> matches the entire word

\{,n\} matches the preceding character up to n times

\{n,\} matches the preceding character at least n times

Group: \ (\) binds one or more characters together and treats them as a whole, such as: \ (root\) \+

1. Cat/proc/meminfo | grep ^[ss].*-o     or Cat/proc/meminfo | Grep-i ' ^s.* 2.grep-v "/bin/bash$"/etc/passwd3.cat/etc/passwd |grep "^RPC:" |cut-d:-f  74.grep "\b[0-9]\? [0-9] [0-9]\b "/etc/passwd   or   grep" \b[0-9]\{2,3\}\b "/etc/passwd 5.grep ' ^[[: space:]]\ + [^ [: space:] ] '  /etc/grub2.cfg6.netstat-tan |grep "listen[[:space:]]*$" 7.cut-d ":"-f1,3/etc/passwd |grep "\<[0-9]\{1,3\} \> "centos6:   cut-d": "-f1,3/etc/passwd |grep" \b[1-9]\? [0-9]\b "-E" \b[0-4][0-9]\{2\}\b "8.grep" ^\ (. *\) \>.*\<\1$ "/etc/passwd  or grep" ^\ (. *\):. *\<\1$ " / ETC/PASSWD9.DF |grep '/dev/sd ' |grep-o ' [0-9]\+% ' |tr-d%|sort-nr extended Regular Expression:   *: Matches the preceding character any time    &n bsp;                          ? : 0 or 1 times                                +  : 1 or more times                                 {m} : Matching M-Times                                  {m,n}: At least m, up to N times                                 a|b:  A or b                               c| Cat:c or cat                               (c|c) at:  cat or cat

The Three Musketeers of Linux text Processing