bash shell 编程练习

原始文件：

find /etc -name passwd 2>&1 | tee ee.log

1. cat -n 把 e.log 的文档内容加上行号后输入 e2.log 这个文档里：

xiluhua@localhost ~/t2scripts $ cat -n e.log | tee e2.log
       /etc/passwd

       find: `/etc/ntp/crypto': Permission denied
       find: `/etc/audisp': Permission denied
       find: `/etc/audit': Permission denied

       find: `/etc/polkit-/localauthority': Permission denied
       find: `/etc/dhcp': Permission denied
      /etc/pam.d/passwd
      find: `/etc/lvm/backup': Permission denied
      find: `/etc/lvm/cache': Permission denied
      find: `/etc/lvm/archive': Permission denied
      find: `/etc/cups/ssl': Permission denied
      find: `/etc/pki/rsyslog': Permission denied

      find: `/etc/pki/CA/private': Permission denied
      find: `/etc/vmware-tools/GuestProxyData/trusted': Permission denied
      find: `/etc/sudoers.d': Permission denied
      find: `/etc/selinux/targeted/modules/active': Permission denied

2. cat -b 把 textfile1 和 textfile2 的文档内容加上行号（空白行不加）之后将内容附加到 textfile3 文档里：

xiluhua@localhost ~/t2scripts $ cat -b e.log | tee e3.log
       /etc/passwd

       find: `/etc/ntp/crypto': Permission denied
       find: `/etc/audisp': Permission denied
       find: `/etc/audit': Permission denied

       find: `/etc/polkit-/localauthority': Permission denied
       find: `/etc/dhcp': Permission denied
       /etc/pam.d/passwd
       find: `/etc/lvm/backup': Permission denied
       find: `/etc/lvm/cache': Permission denied
      find: `/etc/lvm/archive': Permission denied
      find: `/etc/cups/ssl': Permission denied
      find: `/etc/pki/rsyslog': Permission denied

      find: `/etc/pki/CA/private': Permission denied
      find: `/etc/vmware-tools/GuestProxyData/trusted': Permission denied
      find: `/etc/sudoers.d': Permission denied
      find: `/etc/selinux/targeted/modules/active': Permission denied

3. cat /dev/null 清空 ee.log 文档内容：

cat /dev/null > e3.log 

4. chattr  +i：不得任意更动文件或目录。

root@localhost /home/xiluhua/t2scripts $ chattr +i ttt.sh $ 加了 +i 之后，root权限也删不了了
root@localhost /home/xiluhua/t2scripts $ rm -rf ttt.sh
rm: cannot remove `ttt.sh': Operation not permitted

5. chgrp

root@localhost /home/xiluhua/t2scripts # touch ttt.sh
root@localhost /home/xiluhua/t2scripts # ll ttt.sh
-rw-r--r--.  root root  Jan  : ttt.sh
root@localhost /home/xiluhua/t2scripts # chgrp xiluhua ttt.sh
root@localhost /home/xiluhua/t2scripts # ll ttt.sh
-rw-r--r--.  root xiluhua  Jan  : ttt.sh

6. chmod

xiluhua@localhost ~/t2 $ chmod --reference=t.sh tt.sh # 以 t.sh 为原型更改 tt.sh 的权限
xiluhua@localhost ~/t2 $ ll tt.sh
-rwxrwxr-x.  xiluhua xiluhua  Jan  : tt.sh
xiluhua@localhost ~/t2 $ 

7. file (1) 用于辨识文件类型。

xiluhua@localhost ~/t2scripts $ file t.sh -i　　# 显示 mime 类别
t.sh: text/x-shellscript; charset=us-ascii

8. file (2) 显示符号链接的文件类型

xiluhua@localhost ~ $ ln -s t2scripts/ t2

xiluhua@localhost ~ $ file -L  t2
t2: directory

9. cut

xiluhua@localhost ~/t2 $  cat /etc/passwd|head -n |cut -d : -f ,-,
root:::root:/bin/bash
bin:::bin:/sbin/nologin
daemon:::daemon:/sbin/nologin
adm:::adm:/sbin/nologin
lp:::lp:/sbin/nologin

10. lsattr 用于显示文件属性，配合 chattr 命令使用

xiluhua@localhost ~/t2 $ lsattr tt.sh
----i--------e- tt.sh

11. tee

xiluhua@localhost ~/t2 $ cat f3.log | tee f4.log f5.log # 同时输出到 f4和f5 两个文件
abc
efg

12. umask (1)指定在建立文件时预设的权限掩码。

root@localhost ~ # umask

root@localhost ~ # umask -S
u=rwx,g=rx,o=rx

13. umask (2)

xiluhua@localhost ~ $ umask

xiluhua@localhost ~ $ umask -S
u=rwx,g=rwx,o=rx

14. which命令用于查找文件。

which指令会在环境变量$PATH设置的目录里查找符合条件的文件。

15. whereis

root@localhost ~ # whereis bash
bash: /bin/bash /usr/share/man/man1/bash..gz

16. scp (1) 本地到远程

scp install.log xiluhua@192.168.178.132:~

17. scp (2) 远程到本地

scp xiluhua@192.168.178.132:~/rmq_bk_gc.log .

18. awk 是一种处理文本文件的语言，是一个强大的文本分析工具。

19. awk (1)

xiluhua@localhost ~/t2 $ awk '{print $1,$3}' f1.log
 is
 you
This's test
 are

20. awk (2)

xiluhua@localhost ~/t2 $ awk '{printf "%-8s %-10s\n",$1,$4}' f1.log　　# 格式化输出
        a
        like
This's
       orange,apple,mongo

21. awk (3)

提取yum list结果的第三列并除重

root@vm-xiluhua /mnt # yum -q list | awk '{print $3}'| sort -u