linux sort命令以行为单位对文本文件进行排序。
接下来我们会以/tmp/sort_test.txt这个文本文件为例对sort命令的用法进行说明。
sh-# cat /tmp/sort_test.txt
10 my name is xulin
2 I like programming
3 what about you?
sh-#

1. 因为sort命令是按照字符比较的方式进行排序，所以便出现以下的结果，
sh-# cat /tmp/sort_test.txt | sort
10 my name is xulin
2 I like programming
3 what about you?
sh-#

2. 指定-n选项，这样就会以字符串数值大小进行排序，
sh-# cat /tmp/sort_test.txt | sort -n
2 I like programming
3 what about you?
10 my name is xulin
sh-#

3. 如果要反向排序，那就要指定-r选项了，
sh-# cat /tmp/sort_test.txt | sort -nr
10 my name is xulin
3 what about you?
2 I like programming
sh-#

4. 有时候用户希望能够按字段进行排序，其中-t选项用来指定域分隔符，-k用来指定位置，
sh-# cat /tmp/sort_test.txt | sort -t' ' -k 1,2
10 my name is xulin
2 I like programming
3 what about you?
sh-#
sh-# cat /tmp/sort_test.txt | sort -t' ' -k 2,3
2 I like programming
10 my name is xulin
3 what about you?
sh-#

sh-# ifconfig lo
lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:9 errors:0 dropped:0 overruns:0 frame:0
          TX packets:9 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:456 (456.0 b)  TX bytes:456 (456.0 b)

sh-#

sh-# ifconfig lo | sort

          RX bytes:456 (456.0 b)  TX bytes:456 (456.0 b)
          RX packets:9 errors:0 dropped:0 overruns:0 frame:0
          TX packets:9 errors:0 dropped:0 overruns:0 carrier:0
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          collisions:0 txqueuelen:0
          inet addr:127.0.0.1  Mask:255.0.0.0
lo        Link encap:Local Loopback
sh-#

sh-# ifconfig lo | sort -t: -k 2 -n

          collisions:0 txqueuelen:0
lo        Link encap:Local Loopback
          RX packets:9 errors:0 dropped:0 overruns:0 frame:0
          TX packets:9 errors:0 dropped:0 overruns:0 carrier:0
          inet addr:127.0.0.1  Mask:255.0.0.0
          RX bytes:456 (456.0 b)  TX bytes:456 (456.0 b)
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
sh-#

sh-# ifconfig lo | sort -t: -k 2 -nr
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX bytes:456 (456.0 b)  TX bytes:456 (456.0 b)
        &nb