Linux system service Management NTSYSV, log, Exec,xargs, screen, curl,

Source: Internet
Author: User
Tags dmesg

Linux system service Management

1. Linux system service Management

Tool NTSYSV similar to the graphical interface management tool, if the command is not installed using the

Installation:Yum install-y ntsysv

Common services: Crond, iptables, Network, sshd, Syslog, Irqbalance, SendMail, Microcode_ctl

chkconfig--list: Lists the services and whether they are turned on at each level

chkconfig--add/del ServiceName

Turn off or turn on services at a level, 0,1,2,6 level is off by default, just pay attention to the 3,4,5 level

Syntax: Chkconfig--level [level] [service name] on/off

You can also specify multiple levels to turn the AUDITD service off at level 34

Chkconfig--level AUDITD off

Close all the services below all levels

Chkconfig [service name] off

Hosting directory for startup scripts



List of all services in Level 3

lrwxrwxrwx. 1 root root 19 June 1 19:21 k10saslauthd. /init.d/saslauthdlrwxrwxrwx. 1 root root 17 June 3 15:55 s01sysstat. /init.d/sysstat

K10: Indicates the order in which the process was killed

S01: Indicates the order of initiation

The Chkconfig definition description in the service script, each service will have the following definition

# chkconfig:2345 11 88

2345: Is the level of service operation

11: Is the service opening order, this number can be defined by itself, but the number cannot drink other services overlap, after overlapping will cause the service can not start

88: Is the service close order

2. Linux system logs


/var/log/messages Core System log files

Archive one log per week messages-20130901


Messages is generated by the syslogd daemon, and if this service is stopped, the system will not generate/var/log/messages

/var/log/wtmp: View User Login History Last

/var/log/btmp: This is a binary file, you need to use strings to see the content

LASTB Viewing Invalid login history

/var/log/maillog: Mail Log

MAILQ: Check if the message is sent out

/var/log/secure: Records the information used to log in, and the file is also archived.

DMESG: Display boot information for the system

/VAR/LOG/DMESG: The hardware log recorded when the system was started

grep ' '/var/log/maillog

Search for characters related to in the/var/log/maillog file

3. Exec and Xargs

Both exec and find use

Find files with the current directory creation time greater than 10 days and delete

Find. -mtime +10-exec rm-rf {} \;

Bulk Change file name: Find./*-exec mv {} {}_bak \;

Xargs used behind the pipe symbol

Find logs for 10 days ago and delete

Find. -mtime +10 |xargs RM-RF

find/var/log/-type f-mtime +10 |xargs-i mv {} {}.back

The normal files created in the/var/log/directory 10 days ago are all changed to. back end.

-I: Represents a loop, similar to a for

ls-d./* |xargs-n1-i{} MV {} {}_bak

Xargs can turn multiple lines into a row of cat 1.txt|xargs

4. Screen Tool Introduction

Screen is equivalent to a virtual terminal, is not installed by default, it will not be due to network interruption, and each login can enter the screen

Installation: [[email protected] ~]# yum install-y screen

How to use: Directly enter the screen command


View the screen virtual terminal that is already turned on

Exit screen, not end

Ctrl +a then press D to exit the screen session, just exit, and not end.

End: Ctrl +d or enter exit

After exiting, you also want to log in to a screen session again, using Sreen-r Screenid if there is only one screen direct screen-r

Support for name input

screen-s [Name]

Screen-s aming; login words screen-r aming

5. Learn to use the Curl command

Curl is a tool for simple testing of Web Access under the Linux system command line, with a few common options you need to master

Curl-xip:port #-X can specify IP and port, omit write hosts, convenient and practical

Curl-iv #-I can drop the content of the access, only show the status code,-V can show the detailed process

Curl-u User:password #-u can specify user name and password

Curl Http:// (large O) #可以下载

You can also use the-O (Small o) to customize the name

Curl-o index2.html

6. Several network-related commands


Telnet 80


Dig: Domain Name query tool to test whether the domain Name system is working properly

The dig command is not installed by default and needs to be installed to

Installation: Yum install-y bind*

Dig @

NC is not installed by default and needs to be installed

Installation: Yum install-y NC

Nc-z-w2 1-1024 #-w2 indicates a 2s timeout

Port Here you can write only one port, or you can write a range.

When using the NC scan port, you must add-Z or the result will not be displayed.

Also, if you want to display the ports that are not open, you can add a-V

This article is from the It Exchange Learning blog, so be sure to keep this source

Linux system service Management NTSYSV, log, Exec,xargs, screen, curl,

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