linux shell

? Everyone may have found out, because we have part of the formula is repeated, if 1 x 2 = 2 and 2 x 1 = 2 Repeat, then how to solve it? You can find a rule, 1 x 2 =2, 2 x 2 = 4, and 1 x 3 = 3 2 x 3 = 6 3 x 3 = 9, in the same row, the preceding number will not be greater than the subsequent number, i.e. J x i = Z,j will not be greater than I修改部分for i in `seq 9`do for j in `seq 9` do [ $j -le $i ] echo -n "$i x $j = `echo $(($i*$j))` " # 如果 j 小与等于 i 才会打印式子 doneecho ""doneE

If statement 1.1 if statement explanation If is a judgment statement, if the action is similar to [], the general judgment is more or the execution of the statement is more, then will use if 1.2 If format First format if [ 判断条件 ];then 内容else 内容fi Second form, multiple judgments if [ 判断条件 ];then 内容elif [ 判断条件 ];then 内容else 内容fi1.3 Precautions There must be spaces on both sides of [] after the IF statement 1.4 If example1.if ju

In the Linux shell programming, the process control structure and the statement, also is the shell script the emphasis, does not understand the friend, follows the script small compilation together to study.Linux control flow structure learning.One, shell control flow structure1. Control structure 6.while Cycle2.if the

Tags: Shell Linux script programming Automation operationsThis article: Determine whether the user input parameter is a numberHow is the calculation done in the shell? Way One [[emailprotected] scripts]# echo $((1+2)) 3 Way Two Note: When using the method two, the requirements must be spaced. If you are using multiplication, the numbe

================================================= This article for Khler original, reprint must ensure that this article complete and completely retain the original author information and this article original link Author:heyuanhui E-mail:khler@163.com qq:23381103 Msn:pragmac@hotmail.com ================================================= How do I keep the service running? How to ensure that the service can be automatically restarted even if it is dead? This problem is often encountered when writ

Firefox with Tmpfs and automatic rsync.That tattered linuxqq can also use this method to reduce the problem caused by a lot of disk IO.8. Compare remote files with local files with diff ssh [email protected] cat/path/to/remotefile | diff/path/to/localfile- The usual usage of diff is to read two files from a parameter, while the inside of the command is read from stdin.The use of SSH makes web development a lot less cumbersome, and for example SSHFS, can be freed

We will use the common system security configuration as a shell script, only to run this shell script on the server to complete the security settings. Linux system security Settings Shell script is the second update, has been heavily used in a large media web site system, adding some of the previously not thought of s

Small knowledge (take PS as an example): View command path which PScommand to help PS--helpCommand Complete manual: Man PS Description The PS full name is the process status (process state), and he is the one who provides information about the processes. The PS command is used to report the current system's process state. Can be used with the kill command at any time to interrupt, delete unnecessary programs. The PS command is the most basic and powerful process view command that can be used

How to calculate the number of files and directories in the current directory # ls-l * |grep "^-" |wc-l----to count files # ls-l * |grep ' ^d ' |wc-l-----to Count dir How do I just column subdirectories? Ls-f | grep/$ or alias sub = "Ls-f | grep/$ "(Linux) ls-l | grep" ^d "or Ls-ll | grep" ^d "(Solaris) How do I get the specific row contents out of the fileIf you only want to see the first 5 lines of the file,

Net-snmp is a free, open source SNMP implementation, formerly known as UCD-SNMP. Many SNMP are used after its installation, as a monitoring treasure and Aliyun system information monitoring. Let's share the Linux shell script that implements SNMP one-click installation: #!/usr/bin/env Bash Export Lc_all=c if ["$ (id-u)"!= "0"] then echo "This script. Must be run as root 1>2 exit 1 fi ### #check if

To implement Linux under the Shell script batch for the specified folder to add a watermark to the picture, first need to install ImageMagick: Install on CentOS: Yum Install Imagemagick-y Install on Debian: Apt-get Install Imagemagick-y Script: #!/bin/bash for all in/to be processed the picture directory/*{.jpg,.gif} s= ' du-k $each | awk ' {print '} ' if [$s-gt]; then

Linux shell script detects tomcat and restarts automatically Background Run command sh xxx.sh View background tasks: JobsSummoned to the front desk: FG Jobs number The code that can delete the while loop is put into the crontab, and the script can be run directly in the background. #!/bin/bash while [true] do url= "http://www.jb51.net/"; httpok= ' Curl--connect-timeout 10-m--head--silent $url

The meaning of "2>1" in the Linux shell Script: nohup/mnt/nand3/h2000g >/dev/null 2>1 For 1 It is more accurate to say that the file descriptor is 1, and 1 generally represents stdout_fileno, which is actually a dup2 (2) call. He standard output to All_result, then copy standard output to file descriptor 2 (stderr_ Fileno), the consequence is that file descriptors 1 and 2 point to the same file table e

$name >/dev/nullif [$?-eq0];thenstr= "user${name}isdeletesuccessfully!!!" echo-e "\033[30;47m$str\033[0m" elsestr= "user${name}isdeletefailly!!!" echo-e "\033[31;47m$str\033[0m" fi ;; 5) str= ' df-th ' echo-e "\033[30;47m$str\033[0m";; 6) str= ' free -m ' echo-e "\033[30;47m$str\033[0m" ;; 7) clearmenu;; 8) echo-e "\e[31mlogout...\e[0m" sleep1break;; NBSP;NBSP;NBSP;NBSP;NBSP;NBSP;NBSP;NBSP;NBSP;NBSP;NBSP;NBSP;NBSP;NBSP;NBSP;NBSP;9) echo-e "\e[31mquitsuccessfully!!! \e[0m " exit;; *) str= "I

directory ${srcdir} is a directory, otherwise prompt error message and use IF [!-D $desdir]then{usage EC Ho "Error: Destination directory ${desdir} is not directory" exit}fiprocessid=$$; #查找源目录下所有的子目录, output and save to/tmp/srcdir_ process number. txt file, echo "source directory ${srcdir} all subdirectories "Echo"------------------------------"Find $srcdir/*-type D | /usr/bin/tee/tmp/srcdir_tmp_${processid}.txtsed "s/^${srcdir}/${desdir}/g"/tmp/srcdir_tmp_${processid}.txt >/ tmp/srcdir_${proc

. Sometimes we need to read the first line from the BEGIN statement block.We can specify some conditions for the rows that need to be processed, such as:The default field delimiter is a space. We can explicitly specify a delimiter with-F "delimiter": $ awk-f: ' {print $NF} '/etc/passwd$echo | awk ' {' grep root/etc/password | getline cmdout; print Cmdout} ' can read the output of an external shell command into a variable by using Getline cmdoutIn awk

Speaking of function calling, I believe everyone will not be unfamiliar with it. However, for me new to shell, the function calling method in shell is a bit difficult for me and I have taken a lot of detours, because a "natural" error occurred while passing parameters, and I suffered a lot of pains, I would like to sum up the method for calling functions in shell

1. "" "" "The Difference," "The variables will be resolved" "All of them as strings" "to execute system commands 2. The custom variable defaults to a local variable, and the environment variable is a global variable. 3.export can set one or more variables as global variables 4. To use a variable in a child shell in the parent shell, you must set the variable to global with export 5. Commonly used enviro

Often see commands like the following in blogs or forums the curly braces extend brace expansion {} Shell functions Cp/etc/httpd/httpd. {,. Bakup} Or is MV Resume{z,}.doc So what does it mean in the uinx/linux shell command? {} has no practical meaning, but can be used as a brace expansion (curly braces extension or curly braces

Start Linx Shell's first article todayToday describes how PWD and CDs are used.The pwd means "Print working Directory", which displays the current location.PWD also has other available parameters-L (uppercase),-p (uppercase)-L is the same as the PWD showing the current user's location-p Display the user's current physical location and PWD are the sameIn fact, you can use PWD directly.CD can simply think of directory switchingFor example, currently on the/root/desktop, you can switch directly to