Sorting File Contents and Output with sort
Another very useful command to use on text file is sort . As you can probably guess, this command sorts text. If you type sort /etc/passwd , for instance, the content of the /etc/passwd file is sorted in alphabetic order. You can use the sort command on the output of a command also, as in cut -f 1 -d : /etc/passwd | sort , which sorts the contents of the first column in the /etc/passwd file.
[root@rhel7 ~]# cut -f 1 -d : /etc/passwd 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 ~]# cut -f 1 -d : /etc/passwd | sort adm avahi-autoipd bin daemon dbus ftp games halt lp mail nobody operator polkitd postfix root rusky shutdown sshd sync systemd-bus-proxy systemd-network tss
By default, the sort command sorts in alphabetic order（默认是以阿尔法字母排序）. In some cases, that is not convenient because the content that needs sorting may be numeric or in another format. The sort command offers different options to help sorting these specific types of data. Type, for instance, cut -f 3 -d : /etc/passwd | sort -n to sort the third field of the /etc/passwd file in numeric order.(使用sort -n 参数来按数字进行排序)
[root@rhel7 ~]# cut -f 3 -d : /etc/passwd 0 1 2 3 4 5 6 7 8 11 12 14 99 170 999 998 81 997 59 89 74 1000 [root@rhel7 ~]# cut -f 3 -d : /etc/passwd |sort -n 0 1 2 3 4 5 6 7 8 11 12 14 59 74 81 89 99 170 997 998 999 1000
It can be useful also to sort in reverse order; if you use the command du -h | sort -rn , you get a list of files sorted with the biggest file in that directory listed first. （按倒序排序）
[root@rhel7 ~]# cut -f 3 -d : /etc/passwd |sort -rn 1000 999 998 997 170 99 89 81 74 59 14 12 11 8 7 6 5 4 3 2 1 0
You can also use the sort command and specify which column you want to sort. To do this, use sort -k3 -t : /etc/passwd , for instance, which uses the field separator : to sort the third column of the /etc/passwd file. （按第三列进行排序，-t指定分隔符为:）
[root@rhel7 ~]# sort -k3 -t : /etc/passwd root:x:0:0:root:/root:/bin/bash rusky:x:1000:1000:rusky:/home/rusky:/bin/bash operator:x:11:0:operator:/root:/sbin/nologin bin:x:1:1:bin:/bin:/sbin/nologin games:x:12:100:games:/usr/games:/sbin/nologin ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin avahi-autoipd:x:170:170:Avahi IPv4LL Stack:/var/lib/avahi-autoipd:/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 tss:x:59:59:Account used by the trousers package to sandbox the tcsd daemon:/dev/null:/sbin/nologin shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin mail:x:8:12:mail:/var/spool/mail:/sbin/nologin dbus:x:81:81:System message bus:/:/sbin/nologin postfix:x:89:89::/var/spool/postfix:/sbin/nologin polkitd:x:997:995:User for polkitd:/:/sbin/nologin systemd-network:x:998:996:systemd Network Management:/:/sbin/nologin systemd-bus-proxy:x:999:997:systemd Bus Proxy:/:/sbin/nologin nobody:x:99:99:Nobody:/:/sbin/nologin [root@rhel7 ~]#