Linux认证：十五个常用Linux命令行总汇

1. 磁盘使用情况

du -h  查看当前用户每个文件的大小，格式化显示
df  -h  磁盘使用情况

[root@localhost mysql5]# du -h
339M
[root@localhost mysql5]# ls
MySQL-5.5.20-1.linux2.6.i386.tar
MySQL-client-5.5.20-1.linux2.6.i386.rpm
MySQL-devel-5.5.20-1.linux2.6.i386.rpm
MySQL-embedded-5.5.20-1.linux2.6.i386.rpm
MySQL-server-5.5.20-1.linux2.6.i386.rpm
MySQL-shared-5.5.20-1.linux2.6.i386.rpm
MySQL-test-5.5.20-1.linux2.6.i386.rpm
[root@localhost mysql5]# du -h MySQL-client-5.5.20-1.linux2.6.i386.rpm
17M     MySQL-client-5.5.20-1.linux2.6.i386.rpm
[root@localhost mysql5]#

[root@localhost mysql5]# df -h
文件系统              容量  已用 可用 已用% 挂载点
/dev/mapper/VolGroup00-LogVol00
                       14G  6.4G  6.5G  50% /
/dev/sda1              99M   12M   83M  13% /boot
tmpfs                 506M     0  506M   0% /dev/shm

2、常用文件操作命令
cat，显示文件内容。
cd，改变目录路径。
cp，复制文件。
find，查找文件。
grep，搜索、过滤信息。
ls，列出目录信息。
more，分页显示。
rm，删除文件或目录。
vi，调用vi文本编辑器

[root@localhost king]# cat abc1.txt |more//查找当前目录下以a开头的文件
[root@localhost king]# ls
abc1.txt  abc2.txt  abc3.txt  king001  kingtest  new
[root@localhost king]# find -name "a*"
./abc3.txt
./abc1.txt
./abc2.txt

[root@localhost home]# find king -name "a*"
king/abc3.txt
king/abc1.txt
king/abc2.txtgrep查找keyword的所在行的内容
[root@localhost king]# more  abc1.txt|grep "1971"
Federal Election Campaign Act of 1971 to provide bipartisan campaign

ls统计文件个数:原理是ls -l列出多少行 再利用管道作为wc -l输入 以行来数的

[root@localhost king]# ls -l
总计 44
-rwxrw-rw- 1 root root 2395 2012-05-26 abc1.txt
-rwxrw-rw- 1 root root 2397 2012-05-26 abc2.txt
-rwxrw-rw- 1 root root 1020 2012-05-26 abc3.txt
drwxrwxr-x 2 king king 4096 2012-02-02 king001
-rw-rw-r-- 1 king king    0 2012-02-02 kingtest
-rw-r--r-- 1 root root  714 09-30 22:52 new
[root@localhost king]# ls -l|wc -l
7

head  查看文件前20行 tail 查看后面10行

[root@localhost king]# head -20 abc1.txt
[Congressional Record Volume 148, Number 2 (Thursday, January 24, 2002)]
[Daily Digest]
[Page D12]
From the Congressional Record Online through the Government Printing Office []





                        House of Representatives


Chamber Action
Measures Introduced: 13 public bills, H.R. 3622-3634; 8 resolutions, H.
Con. Res. 302-308, and H. Res. 335 were introduced.
  Page H78
Reports Filed: No reports were filed today.
Speaker Pro Tempore: Read a letter from the Speaker wherein he
appointed Representative Shimkus to act as Speaker pro tempore for
today.

[root@localhost king]# tail -10 abc1.txt
Res. 203, providing for consideration of H.R. 2356, to amend the
Federal Election Campaign Act of 1971 to provide bipartisan campaign
reform, the motion was referred to the Calendar of Motions to Discharge
Committees.
  Pages H76-77
Senate Message: Message received from the Senate appears on page H39.
Quorum Calls--Votes: One yea-and-nay vote developed during the
proceedings of the House today and appears on pages H47-48. There were
no quorum calls.
Adjournment: The House met at 10 a.m. and adjourned at 3:38 p.m.

Linux命令经典面试题：统计文件中出现次数最多的前10个单词

使用linux命令或者shell实现：文件words存放英文单词，格式为每行一个英文单词（单词可以重复），统计这个文件中出现次数最多的前10个单词。

cat words.txt | sort | uniq -c | sort -k1,1nr | head -10

　　主要考察对sort、uniq命令的使用，相关解释如下，命令及参数的详细说明请自行通过man查看，简单介绍下以上指令各部分的功能：

sort:  对单词进行排序

uniq -c:  显示唯一的行，并在每行行首加上本行在文件中出现的次数

sort -k1,1nr:  按照第一个字段，数值排序，且为逆序

head -10:  取前10行数据

[root@localhost king]# uniq -c word.txt|sort -k1
      1 bye
      1 good
      1 see
      1 tim
      1 tim
      1 you
      2 jack
      2 king
[root@localhost king]# uniq -c word.txt|sort -r|head -2
      2 king
      2 jack