http://heipark.iteye.com/blog/1083805
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 count 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}
Only allow root Telnet cd/etc
Touch Nologin
Lock user, view machine 64-bit or 32-bit uname-m #会显示: "i686", "x86_64" cannot telnet (root only) passwd-l Hadoop
Unlock user (root only) passwd-u Hadoop
Lists the file paths of the RPM installer RPM-QL hadoop-0.20
View system already installed software 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 ipvi/etc/resolv.conf
#查看内存free
#查看CPU是否支持64操作系统, if the result is greater than 0, the description supports 64bit mode (long mode)
Cat/proc/cpuinfo | grep Flags | grep ' LM ' | Wc-l
#查看某行内容
Sed-n ' 100{p;q} ' filename
#查看用户所属组
grep "User name"/etc/group
#查看rpm包文件
Rpm2cpio hadoop.rpm | Cpio-idmv
#添加某个路径到运行时库, one line of 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
#centos下通过shell修改文件扩展名, 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 removes 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
The Linux command line parameter references the Run 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 Write # method one
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 a line command to create a user and set a password useradd-p ' OpenSSL passwd <pwd> '-G <group_ Name> <username>
Create a user and disable Telnet useradd-s/sbin/nologin AK47
Query user crontab run record Cat/var/log/cron | grep <username>
Modify the Linux User directory usermod-d/home/hdfs-u hdfs disk speed test hdparm-t/dev/sda1
Quick Find file (according to file name) # Locate command is responsible for finding, updatedb command generating file index (daily)
Locate *qq*.txt
Chkconfig wrote Chkconfig--list | More # List all system services
Chkconfig <service_name> Off|on # Shut down, turn on system services
The first SSH login is not prompted to configure the SSH conf file stricthostkeychecking No
Top C # Display 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 repetitions (shell-implemented group by + count) # Uniq must first sort,uniq the parameter-C to print the group repeat number
Cat xx. TXT | Sort | Uniq-c
The tar command uses TAR-ZCF my.tgz my # compression 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 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 writes # finds lines in text that contain boy and girl
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
See the number of open files Lsof |wc-l
Lsof-p PID |wc-l
See which programs are using Disk Iotop
Create large file writes 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
Linux command notes
