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  • Filtering Specific Columns with cut

      Filtering Specific Columns with cut  

      When working with text files, it can be useful to filter out specific fields. Imagine that you need to see a list of all users in the /etc/passwd file. In this file, several fields are defined, of which the first contains the name of the users who are defined. To filter out a specific field, the  cut  command is useful. To do this, use the  -d  option to specify the field delimiter(-d参数指定分隔符) followed by  -f  with the number of the specific field you want to filter out(-f参数指出你要过滤哪一个fields). So, the complete command is  cut -d : -f 1 /etc/passwd  if you want to filter out  the first field of the /etc/passwd file. You can see the result bellow:

    [root@rhel7 ~]# cat /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
    sync:x:5:0:sync:/sbin:/bin/sync
    shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
    halt:x:7:0:halt:/sbin:/sbin/halt
    mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
    operator:x:11:0:operator:/root:/sbin/nologin
    games:x:12:100:games:/usr/games:/sbin/nologin
    ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
    nobody:x:99:99:Nobody:/:/sbin/nologin
    avahi-autoipd:x:170:170:Avahi IPv4LL Stack:/var/lib/avahi-autoipd:/sbin/nologin
    systemd-bus-proxy:x:999:997:systemd Bus Proxy:/:/sbin/nologin
    systemd-network:x:998:996:systemd Network Management:/:/sbin/nologin
    dbus:x:81:81:System message bus:/:/sbin/nologin
    polkitd:x:997:995:User for polkitd:/:/sbin/nologin
    tss:x:59:59:Account used by the trousers package to sandbox the tcsd daemon:/dev/null:/sbin/nologin
    postfix:x:89:89::/var/spool/postfix:/sbin/nologin
    sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
    rusky:x:1000:1000:rusky:/home/rusky:/bin/bash
    [root@rhel7 ~]# cut -d : -f 1 /etc/passwd   --以冒号为分隔,filter第一部分
    root
    bin
    daemon
    adm
    lp
    sync
    shutdown
    halt
    mail
    operator
    games
    ftp
    nobody
    avahi-autoipd
    systemd-bus-proxy
    systemd-network
    dbus
    polkitd
    tss
    postfix
    sshd
    rusky
    [root@rhel7 ~]# 
    

     或者以冒号为分隔,filter第二部分结果如下:

    [root@rhel7 ~]# cut -d : -f 2 /etc/passwd  
    x
    x
    x
    x
    x
    x
    x
    x
    x
    x
    x
    x
    x
    x
    x
    x
    x
    x
    x
    x
    x
    x
    
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  • 原文地址:https://www.cnblogs.com/rusking/p/5590232.html
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