Week six Homework

1. Copy the/etc/rc.d/rc.sysinit file to the/tmp directory and add # to the beginning of the line with at least one whitespace character in the/tmp/rc.sysinit file;

Only CentOS 6 has this file.

# cp/etc/rc.d/rc.sysinit/tmp/# Vim/tmp/rc.sysinit

Input: (enter the last line mode)

:%s/^[[:space:]]/#&/

s/what to look for/replace with content/modifiers

%: Full text, equivalent to 1,$

&: Referring to the entire content found in the previous lookup

2, copy/boot/grub/grub.conf to/tmp directory, delete the blank character of the beginning of the/tmp/grub.conf file;

# cp/boot/grub/grub.conf/tmp/# Vim/tmp/grub.conf

Last-line mode

:%s/^[[:space:]]\+//

3. Remove the # and white space characters from the/tmp/rc.sysinit file that begin with # and followed by at least one white-space character

Topic unintelligible

# Vim/tmp/rc.sysinit

Last-line mode

:%s/^#[[:space:]]\+//

4. Add # to the beginning of the first three lines in the/tmp/grub.conf file;

# vim/tmp/grub.conf

Last-line mode

: 1,3s/^/#&/

5. Change the last 0 of all enabled=0 or gpgcheck=0 in the/etc/yum.repos.d/centos-media.repo file to 1;

# Vim/etc/yum.repos.d/centos-media.repo

Last-line mode

: s/=0/=1/

6, every 4 hours to perform a backup of the/etc directory, back up to the/backup directory, save the directory named Shape etc-201608300202

7, weekly 2,4,6 backup/var/log/messages file to/backup/messages_logs/directory, save the file name like messages-20160830

8, every two hours every day to take the current system/proc/meminfo file in the beginning of all the information in the S./stats/memory.txt file

9, working days of work time, every two hours to perform the echo "Howdy"

# date +%y%m%d%h%m201609101425

# crontab-e #编辑定时任务 # crontab-l #查询 # crontab-l #移除所有任务

crontab file format: minutes hours Sun moon Day Day commands

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*: On behalf of each time unit is executed once, the first "*" represents the execution of every minute (here and the specific time unit is easy to confuse)

*/n: Execute once every n time unit

N-M: Continuous Time range

Cp-a: Equivalent to-DR--preserv=all replication, all attributes are retained, and if the source file is the attribute of the linked file, the link file property is copied instead of the file itself

+: Specify the time format, %y represents the year,%m represents the month, and%d represents the day,%h represents the hour, and%m represents minutes

' Command ': Back quotes inside for command

Note: Need to be clear * meaning, from small to large for specific time units (seconds, minutes) defined

Script Programming Exercises

10, create the directory/tmp/testdir-the current date and time;

# mkdir-pv/tmp/testdir-' Date ' +%f%T "' mkdir: Directory Created"/tmp/testdir-2016-09-10 "

-P: exists in no error, and can automatically create the required directories;

-V: Show more information

11. Create 100 empty files in this directory: file1-file100

#/bin/bash# The first line specifies the program that interprets the script command for I in ' seq ';d o touch file$i Done

Syntax 1

For variable name in list;

Loop body

Done

Syntax 2

For (variable initial value; loop control condition; variable change expression); Do

Loop body

Done

12. Display the user name of the user who is located in the/etc/passwd file in the first even row;

#!/bin/bash

#

Sed-n ' n;p '/etc/passwd | Cut-d ': '-f1

SED options

-N: Use Quiet (silent) mode. In the usage of general sed, all data from STDIN is generally listed on the terminal. However, if you add the-n parameter, only the line (or action) that is specially processed by SED is listed.

SED command

N: Reads the next line of matching rows to the pattern space

P: Display the contents of the mode space

Cut command

-d ': '-f1 takes the 1th field with a colon delimiter

13. Create 10 user user10-user19, password and user name;

#!/bin/bash

#

For i in {10..19};d o

ID user$i &>/dev/null && echo "The user is exists" | | Useradd user$i && echo "user$i" |passwd--stdin user$i &>/dev/null

Done

Output redirection

&>: Overwrite redirection ( merge standard output and error output redirect for the same data stream)

&>/dev/null: standard output redirects to an empty device file, does not output any information to the terminal

Logical operations

&& Logic and

Command 2 does not execute when command 1 is executed correctly

Command 2 does not execute when command 1 is not executed correctly

|| Logical OR

Command 2 does not execute when command 1 is executed incorrectly

Command 2 does not execute when command 1 is executed correctly

Modify user passwords in a non-interactive manner

echo "PASSWORD" | Passwd–stdin USERNAME

14, create 10 empty files file10-file19 in/tmp/;

Script

#!/bin/bash

#

For i in {10..19};d o

Touch/tmp/file$i

Done

Command line

# Touch File{10..19}

15. Change the file10 and the genus to user10, and so on.

#/bin/bash

#

For i in {10..19}; Do

if [-e/tmp/file$i];then

Chown user$i:user$i/tmp/file$i

else echo "No such file."

Fi

Done

Grammar

If double Branch statement

If [conditional judgment]

Then

Conditions for the establishment of implementation

Else

Conditions do not set up the implementation

Fi

Week six Homework