• awk实例


    awk
    FS:输入字段分隔符
    OFS:输出字段分隔符
    RS:输入时的换行符
    ORS:输出的换行符
    NF:字段数量
    $NF:最后一个字段
    NR:统计行数
    FNR:各个文件的行数统计
    FILENAME:当前处理的文件名路径
    ARGC:命令行参数的个数
    ARGV:数组,以ARGV($1,...)调用
    1.[root@localhost ~]# awk -v FS=":" '{print $1}' /etc/passwd
    [root@localhost ~]# awk  '{print $1}' /etc/passwd
    [root@localhost ~]# gawk -v FS=":" '{print $1}' /etc/passwd相当于[root@localhost ~]# gawk -F: '{print $1}' /etc/passwd
    [root@localhost ~]# awk -v FS=":" '{print $1,$3,$7}' /etc/passwd
    [root@localhost ~]# awk -v FS=':' '{print $1,$3,$7}' /etc/passwd
    [root@localhost ~]# awk -v FS=':' -v OFS='#' '{print $1,$3,$7}' /etc/passwd
    [root@localhost ~]# awk -v RS=':' -v ORS='#' '{print}' /etc/passwd
    root#x#0#0#root#/root#/bin/bash
    bin#x#1#1#bin#/bin#/sbin/nologin
    daemon#x#2#2#daemon#/sbin#/sbin/nologin
    adm#x#3#4#adm#/var/adm#/sbin/nologin
    lp#x#4#7#lp#/var/spool/lpd#/sbin/nologin
    
    [root@localhost ~]# awk '{print NF}' /etc/fstab 统计行字段个数;
    
    [root@localhost ~]# awk '{print $NF}' /etc/fstab cat /etc/fstab 显示最后一个字段
    
    [root@localhost ~]# awk 'BEGIN{print ARGC}' /etc/fstab /etc/issue
    3
    [root@localhost ~]# awk 'BEGIN{print ARGV[0]}' /etc/fstab /etc/issue
    awk
    [root@localhost ~]# awk -v test='glq hello' '{print test,$1}' /etc/fstab 
    glq hello 
    glq hello #
    glq hello #
    glq hello #
    [root@localhost ~]# awk 'BEGIN{test="welcome";print test,$2}' /etc/fstab 
    welcome 
    [root@localhost ~]# awk -v test='to my log' '{print test,$2}' /etc/fstab 
    to my log 
    to my log 
    to my log /etc/fstab
    to my log Created
    to my log 
    to my log Accessible
    [root@localhost ~]# awk -F: -v test="my log" '{print test,$7}' /etc/passwd
    my log /bin/bash
    my log /sbin/nologin
    my log /sbin/nologin
    
    ----------------------------
    
    printf
    [root@localhost ~]# awk -F: '{printf "username: %-15s,UID: %d
    ",$1,$3}' /etc/passwd
    username: root           ,UID: 0
    username: bin            ,UID: 1
    username: daemon         ,UID: 2
    username: adm            ,UID: 3
    [root@localhost ~]# awk -F: '{printf "username: %-10s,UID: %-1d,   Shell: %s
    ",$1,$3,$7}' /etc/passwd
    username: root      ,UID: 0,   Shell: /bin/bash
    username: bin       ,UID: 1,   Shell: /sbin/nologin
    username: daemon    ,UID: 2,   Shell: /sbin/nologin
    [root@localhost ~]# awk -F: '{printf "username: %-10s UID: %-1d   Shell: %s
    ",$1,$3,$7}' /etc/passwd
    username: root       UID: 0   Shell: /bin/bash
    username: bin        UID: 1   Shell: /sbin/nologin
    username: daemon     UID: 2   Shell: /sbin/nologin
    
    if判断语句:
    [root@localhost ~]# awk -F: '{$3>=1000?usertype="common user":usertype="system user";printf "%15s:%-s
    ",$1,usertype}' /etc/passwd
               root:system user
                bin:system user
             daemon:system user
                adm:system user
    ---------------------------------------
    [root@localhost ~]# awk '/^UUID/{print $1}' /etc/fstab 
    UUID=63539c8b-2d17-4c5e-aa11-e232515bba61
    [root@localhost ~]# awk '!/^UUID/{print $1}' /etc/fstab 
    
    #
    #
    #
    #
    #
    #
    #
    /dev/mapper/centos-root
    /dev/mapper/centos-swap
    [root@localhost ~]# awk -F: '$3<1000{print "user:"$1,$3}' /etc/passwd
    user:root 0
    user:bin 1
    user:daemon 2
    user:adm 3
    user:lp 4
    user:sync 5
    [root@localhost ~]# awk -F: '$NF=="/bin/bash"{print $1,$NF}' /etc/passwd
    root /bin/bash
    testdb /bin/bash
    test1 /bin/bash
    [root@localhost ~]# awk -F: '$NF~/bash$/{print $1,$NF}' /etc/passwd
    root /bin/bash
    testdb /bin/bash
    test1 /bin/bash
    [root@localhost ~]# awk -F: '/^root/,/^ftp/{print $1}' /etc/passwd
    root
    bin
    daemon
    adm
    lp
    sync
    shutdown
    halt
    mail
    operator
    games
    ftp
    [root@localhost ~]# awk -F: '(NR>2&&NR<=10){print $1}' /etc/passwd
    daemon
    adm
    lp
    sync
    shutdown
    halt
    mail
    operator
    
    BEGIN和END使用:
    [root@localhost ~]# awk -F: 'BEGIN{print "username             UID 
    ------------------------"}{printf "%-21s %s
    ",$1,$3}' /etc/passwd
    username             UID 
    ------------------------
    root                  0
    bin                   1
    daemon                2
    adm                   3
    lp                    4
    sync                  5
    shutdown              6
    halt                  7
    mail                  8
    operator              11
    games                 12
    ftp                   14
    nobody                99
    avahi-autoipd         170
    systemd-bus-proxy     999
    systemd-network       998
    dbus                  81
    polkitd               997
    tss                   59
    postfix               89
    sshd                  74
    mysql                 27
    testdb                1000
    test1                 1001
    [root@localhost ~]# awk -F: 'BEGIN{print "username             UID 
    ------------------------"}{printf "%-21s %s
    ",$1,$3}END{print                  "end 
    ----------------------"}' /etc/passwd
    username             UID 
    ------------------------
    root                  0
    bin                   1
    daemon                2
    adm                   3
    lp                    4
    sync                  5
    shutdown              6
    halt                  7
    mail                  8
    operator              11
    games                 12
    ftp                   14
    nobody                99
    avahi-autoipd         170
    systemd-bus-proxy     999
    systemd-network       998
    dbus                  81
    polkitd               997
    tss                   59
    postfix               89
    sshd                  74
    mysql                 27
    testdb                1000
    test1                 1001
    end 
    ----------------------
    
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  • 原文地址:https://www.cnblogs.com/ligao/p/6393345.html
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