Awk Getting started with a detailed

I. Overview of AWK

"Oz"

awk: report Generator, format print

Format each field of each row read in the file, and then display

Internal support variables, conditional judgments, loops, arrays

awk--New awk--Nawk (fee)

GNU awk---Gawk "Sue"

Ii. Use of awk

awk and default are delimited by any whitespace character, while cut defaults to a tab and can only be specified with a single space character as a delimiter

Note: Use "Do not use" as sed is easy to error

Usage format:

awk [OPTIONS] ' SCRIPT ' FILE ...

awk [OPTIONS] ' pattern/{action} ' File ...

Action

Print, default printing

Pattern

Include Address delimitation:

/pat1/,/pat2/

/pattern/

！ /pattern

Expression: Expressions: >,<,=,>=,<=,=,!=,~

BEGIN: preparatory work before execution

END: Finishing work after execution

Four types of separators commonly used by awk:

Input:

Line delimiter: Default line break: "$", cat-a can view all white-space characters of a file

Field delimiter: Default tab

Output:

Line delimiter: Default line break: "$"

Field delimiter: Blank

awk built-in variables:

$1,$2,$3 ...: 2nd field, 2nd field, 3rd field ...

$ A: Indicates the entire row

$NF: Indicates the last field, NF: Indicates the total number of fields

FS: The field delimiter used when reading the entry. Default Blank

OFS: The field delimiter used when outputting rows. Default Blank

[[email protected] shell]# awk -f :  '/^root/ {print $1} '  /etc/ passwdroot[[email protected] shell]# awk -f:  '/^\<root\>/ {print $1} '  /etc/passwd   root[[email protected] shell]# awk -F :  '/^ root/ {print $1,$7} '  /etc/passwd      #逗号只是命令的一部分, not the result of the output root /bin /bash[[email protected] shell]# awk -f :  '/^root/ {print $1$7} '  / etc/passwdroot/bin/bash[[email protected] shell]# awk -f:  '/^\<root\>/ { print username $1,$7} '  /etc/passwdroot /bin/bash[[email protected] shell]#  awk -f:  '/^\<root\>/ {print username sb$1,$7} '  /etc/passwdroot /bin/ bash[[email protected] shell]# awk -f:  '/^\<root\>/ {print username &NBSP;SB&NBSP;$1,$7}'  /etc/passwdroot /bin/bash[[email protected] shell]# awk -F:  '/^\<root\ >/ {print  "USERNAME&NBSP;SB"  $1,$7} '  /etc/passwdusername sbroot /bin/bash[[ email protected] shell]# awk -f:  '/^\<root\>/ {print  ' username  sb  " $1,$7}  /etc/passwdusername sb root /bin/bash[[email protected]  shell]# ^c[[email protected] shell]# awk -f:  '/^\<root\>/ {print   "username sb "  $1,nihao$7} '  /etc/passwdusername sb root /bin/bash[[ email protected] shell]# awk -f:  '/^\<root\>/ {print  ' username  sb  " $1," Nihao "$7} '  /etc/passwdusername sb root nihao/bin/bash[[email  protected] shell]# awk -f:  '/^\<root\>/ {print  "username sb "  $1, "Nihao" $7SB} '  /eTc/passwdusername sb root nihao/bin/bash[[email protected] shell]# awk -f:   '/^\<root\>/ {print  ' username sb  " $1," Nihao "$7" SB "} '  /etc/ Passwdusername sb root nihao/bin/bashsb[[email protected] shell]# awk -f:   '/^\<root\>/ {print  ' username sb  " $1," Nihao "$7" \NSB "} '  /etc/ Passwdusername sb root nihao/bin/bashsb

[[email protected] shell]# df -h|awk   ' {print $1} ' Filesystem/dev/sda2tmpfs/ dev/sda1/dev/sda5[[email protected] shell]# df -h|awk   ' {print $2} ' size29g495m477m68g[[email protected] shell]# df -h|awk   "{print $2}"   filesystem      size  used avail use% mounted on/ Dev/sda2        29g  4.6g   23g  17 % /tmpfs           495m      0  495M   0% /dev/shm/dev/sda1        477m   28m  424m   7% /boot/dev/sda5         68G  4.3G   60G   7% /usr[[email  Protected] shell]# df -h|awk   ' {print} '    Filesystem      Size   Used Avail Use% Mounted on/dev/sda2         29g  4.6g   23g  17% /tmpfs            495m     0  495m   0% /dev/shm/ Dev/sda1       477m   28m  424m   7 % /boot/dev/sda5        68g  4.3g   60g    7% /usr

1, take/etc/passwd the UID is greater than 500 user name

[Email protected] shell]# awk-f: ' $3>=500{print ' Username: ' $ '/etc/passwd Username:testbashUsername:ba SherUsername:nologinUsername:fedoraUsername:user1Username:bash1Username:xjUsername:OracleUsername:bashUsername : XxjUsername:openstackUsername:centos

2. Take/etc/passwd to the end of bash

[[email protected] shell]# awk -f:  ' $7~/bash$/{print} '  /etc/passwdroot:x:0:0: chfn root:/root:/bin/bashtestbash:x:501:501::/home/testbash:/bin/bashbasher:x:502:502::/home/basher:/bin/ Bashfedora:x:504:504::/home/fedora:/bin/bashuser1:x:505:505::/home/user1:/bin/bashbash1:x:506:506::/home/bash1 :/bin/bashxj:x:507:507::/home/xj:/bin/bashoracle:x:3000:3000::/home/database:/bin/bashbash:x:3001:3001::/home/ Bash:/bin/bashxxj:x:3002:3002::/home/xxj:/bin/bashopenstack:x:3003:3003::/home/openstack:/bin/bashcentos:x :3004:3004::/home/centos:/bin/bash[[email protected] shell]# awk -f:  '/bash$/{print   "sbsb: " $} '  /ETC/PASSWD          SBSB:  ROOT:X:0:0:CHFN ROOT:/ROOT:/BIN/BASHSBSB: TESTBASH:X:501:501::/HOME/TESTBASH:/BIN/BASHSBSB:  basher:x:502:502::/home/basher:/bin/bashsbsb: fedora:x:504:504::/home/fedora:/bin/bashsbsb:  User1:x:505:505::/home/user1:/BIN/BASHSBSB: BASH1:X:506:506::/HOME/BASH1:/BIN/BASHSBSB: XJ:X:507:507::/HOME/XJ:/BIN/BASHSBSB:  Oracle:x:3000:3000::/home/database:/bin/bashsbsb: bash:x:3001:3001::/home/bash:/bin/bashsbsb:  xxj:x:3002:3002::/home/xxj:/bin/bashsbsb: openstack:x:3003:3003::/home/openstack:/bin/bashsbsb:  centos:x:3004:3004::/home/centos:/bin/bash[[email protected] shell]# awk -f:  ' $7== '/ Bin/bash " {print $1}  /etc/passwd   Roottestbashbasherfedorauser1bash1xjoraclebashxxjopenstackcentos

Begin,end:

[[email protected] shell]# awk -f:  ' $3>=500 {print  '-------------\ n "$ '  /etc/passwd ------------- Testbash-------------basher-------------nologin-------------Fedora-------------user1-------------bash1-------------XJ---- ---------Oracle-------------bash-------------xxj-------------openstack-------------centos[[email  protected] shell]# awk -f:  ' begin{print  "username\n----------"}$3>=500 {print  $1} '  /etc/ Passwdusername----------testbashbashernologinfedorauser1bash1xjoraclebashxxjopenstackcentos[[email  protected] shell]# awk -f:  ' $3>=500 {print $1}end{print  '-------"} '  /etc/passwdtestbashbashernologinfedorauser1bash1xjoraclebashxxjopenstackcentos-------[[email  protected] shell]# awk  ' begin{fs= ': "} $3>=500 {print $7}  '  /etc/ passwd/bin/bash                            #用BEGIN指定分隔符/ Bin/bash/sbin/nologin/bin/bash/bin/bash/bin/bash/bin/bash/bin/bash/bin/bash/bin/bash/bin/bash/bin/bash

Practice:

1, the group showing GID less than 500

# awk-f: ' $3<500{print $ '

2. Display the default shell for Nologin users

# awk-f: '/\<nologin$/{print '} '

# awk-f: ' $7== '/sbin/nologin ' {print '} '

3. Display the configuration information of the Eh0 network card file, note that only the value after = is displayed

# awk-f= ' {print $} '

4. Display the kernel parameters defined in the/etc/sysctl.conf file, display only the name

5, display eth0 network card IP address, through the ifconfig command result to filter

# ifconfig Eth0|awk '/inet addr/{print} ' |awk-f: ' {print $} ' |awk ' {print '} '

Awk Getting started with a detailed