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
This article is from the "Richy Operations Log" blog, please make sure to keep this source http://richylu.blog.51cto.com/1481674/1846352
Common Linux Basic commands