Common Linux Basic commands

Allow non-root users to use "sudo"

Root login system, execute "visudo", add a new rule according to the example (remember the password entered is the current user password, not the root password)

#不需要密码执行sudo命令

Hadoop all= (All) Nopasswd:all

Date

Time Stamp to date

Date-d ' 1970-01-01 UTC 1312438633.724 seconds ' + "%y-%m-%d%T"

#显示现在日期

Echo ' date-d now +%y%m%d '

#显示昨天日期

Echo ' date-d yesterday +%y%m%d '

#加减时间

Date +%y%m%d–date= "-1 day"

Date +%y%m%d%h–date= "-1 hour"

See what the site is server

Curl-s–head "Http://www.baidu.com"

View Redhat version

Cat/etc/redhat-release #我这里显示 "CentOS release 5.5 (Final)"

View Linux Max Open file number wrote

Ulimit-a

# Focus on the screen display one line, you can see the maximum number of open files is 1024

Open files (-N) 1024

To set the number of open files:

Echo-ne "

* Soft Nofile 65536

* Hard Nofile 65536

">>/etc/security/limits.conf

After the launch of the terminal, in the implementation of ULIMIT-A, you can see that the changes have taken effect

Zip compressed file

Zip {dist} {src}

zip-p {password} {dist} {src}

Allow root login only

Cd/etc

Touch Nologin

Lock the user to see whether the machine is 64-bit or 32-bit

Uname-m #会显示: "i686", "x86_64"

Unable to Telnet (root only)

Passwd-l Hadoop

Unlock user (root only)

Passwd-u Hadoop

List the file paths of the RPM Setup program

RPM-QL hadoop-0.20

View system has software installed

Rpm-qa | grep Hadoop

View current server total CPU cores (number of cores)

More/proc/cpuinfo | grep ' Processor ' | Wc-l

#查看每个CPU的核数

More/proc/cpuinfo | grep ' CPU cores '

#计算当前服务cpu数量

Total number of cores/cores per CPU

#查看CPU位数

Getconf Long_bit

To view the installation path for a program

Whereis Java

View the path to the execution program

which Java

Modify DNS IP

Vi/etc/resolv.conf

View Memory

Free

See if the CPU supports 64 operating systems

If the result is greater than 0, the description supports 64bit mode (long mode)

Cat/proc/cpuinfo | grep Flags | grep ' LM ' | Wc-l

View a line of content

Sed-n ' 100{p;q} ' filename

To view groups to which the user belongs

grep "User name"/etc/group

View RPM Package Files

Rpm2cpio hadoop.rpm | Cpio-idmv

Add a path to the run-time library, one line at a path

Vi/etc/ld.so.conf

/usr/local/lib/

(or use an environment variable in such a way that does not require root access)

Export ld_library_path=/xxxxx: $LD _library_path

Modify file extensions via Shell under CentOS

Rename <oldname> <newname> <*.files>

#将所有html扩展名改为htm扩展名

Rename. html. htm *.html

Specific reference: http://www.cyberciti.biz/tips/renaming-multiple-files-at-a-shell-prompt.html

#通过mv也可以实现修改扩展名这个功能

MV GoodYear. {htm,html}

Sort command

#-U Remove Duplicate rows

#-R Descending (default to Ascending)

#-O output sorted after data, he with redirect ' > ' The biggest difference is the output data to the original file

Sort Seq.txt-o > Seq.txt

#-N Sort by numeric size

#-k Specifies sorting according to a column

Sort Num.txt-k2 # Sorted by second column (default delimiter is space, tab)

#-T specifies the column delimiter, only one character is supported

#-M Merge sort

Linux command line parameter reference

To run the command:

./test.sh 111 222 333 444

Echo Run file name: $

#./test.sh

Echo First parameter: $

#111

echo number of parameters: $#

#4

Echo Last: $_

#444

echo all parameters, parameters are considered to be multiple strings: [email protected]

#111 222 333 444

echo all parameters, parameter is considered a string: $*

#111 222 333 444

echo Program PID: $$

Echo Exit code: $?

Less command

TIP1: Typing 50p, can enter 50% of the document location, support decimals, such as 95.5p

Script Change Password

#方法一

echo 123123 |passwd–stdin ABC

#方法二

#echo "Root:[email protected]# $QW 12qw" |chpasswd

#pwdadm-C Root

Http://www.aixchina.net/club/thread-69699-1-1.html

One-line command to create a user and set a password

Useradd-p ' OpenSSL passwd <pwd> ' G <group_name> <username>

Create users and disable remote logins

Useradd-s/sbin/nologin AK47

Querying user crontab Running records

Cat/var/log/cron | grep <username>

Modifying the Linux User directory

usermod-d/home/hdfs-u HDFs

Disk Speed test

Hdparm-t/dev/sda1

Quick Find files (based on file name)

# Locate command is responsible for finding, updatedb command generating file index (daily)

Locate *qq*.txt

Chkconfig

Chkconfig–list | More # List all system services

Chkconfig <service_name> Off|on # Shut down, turn on system services

First SSH login not prompted

Configuring the SSH conf file stricthostkeychecking No

Top

C # Show program full path

M # Sort by memory

P # Sorted by CPU

Top-p <pid> # View Process Top

#RES表示物理内存占用, the PS command is RSS representation of physical memory

BZ2 File Decompression

BUNZIP2 yy.bz2

View the number of repetitions (shell-implemented group by + count)

# Uniq must first sort,uniq parameter-C, print group repeats the number of times

Cat xx. TXT | Sort | Uniq-c

The TAR command uses

TAR-ZCF my.tgz my # Compressed packaging

TAR-CF my.tgz My # do not compress packaging

TAR-ZXF my.tgz My # Unpacking package

TAR-XF my.tgz my # Uncompressed package

TAR-TF # View the TAR package structure

Find

#-o: Or condition

# Find all the. htm and. html files at the end of the current directory

Find. \ (-name "*.htm"-o-name "*.html" \)

#-a:and Conditions

Grep

#查找文本中包含boy和girl的行

Cat My.txt | Grep-e ' Boy|girl '

# Find file name based on text content, "-h" for output file name

Find. -name ' *city* '-ls-exec zgrep ' null ' {}-h \;

# "or" lookup

Method One: grep ' pattern1\|pattern2 ' filename

Method Two: grep-e ' pattern1|pattern2 ' filename

Method Three: Egrep ' pattern1|pattern2 ' filename

Method Four: grep-e pattern1-e pattern2 filename

# "and" lookup

Method One: grep-e ' pattern1.*pattern2 ' filename

Method Two: grep-e ' pattern1 ' filename | Grep-e ' pattern2 '

Modify hostname

Method One: hostname <new hostname>

Method Two: Vi/etc/sysconfig/network

To view the number of open files

Lsof |wc-l

Lsof-p PID |wc-l

See which programs are using disk

Iotop

Create a large file

DD If=/dev/zero of=test bs=1m count=1000

#更大文件可以用下面这个, come on.

DD If=/dev/zero of=test bs=1m count=0 seek=100000

Create a simulated n multiple small file

For

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Common Linux Basic commands