what is shell scripting

The while loop is used to continuously execute a series of commands and to read data from the input file; the command is usually a test condition. The format is:While Commanddo Statement (s) to being executed if command is TruedoneThe command finishes, control returns to the top of the loop, and starts from the beginning until the test condition

Script This article originates from: http://phpuser.com Author: y10k translation (2002-10-15-06:02:00) --English Original: Darrell Brogdon, published in Http://www.phpbuilder.com/columns/darrell20000319.php3) Many people may have wanted to use PHP to write some of the regular mail, such as the program, but there is no way to execute PHP on a regular basis; when I went to Phpbuilder, I found this article, so I want to give you a translation (at the sa

% $Y 3 · [Email protected] ~]# ycube=expr $Y \* $Y \* $Y [Email protected] ~]# echo $Ycube 4096 · ################### #Position variable #################### represented as $n, n is a number between 1~9 · [Email protected]/]# VI add.sh #!/bin/bash sum=expr $1 + $2 echo "$ + $ = $SUM" · [Email protected] ~]# chmod +x add.sh · [Email protected]/]#./add.sh 12 34 12 + 34 = 46 · ################### #Predefined variable #################### $#: Number of po

-50.png "alt=" Wkiol1mdkm2jz6uoaabbjl5wdhm575.png "/>650) this.width=650; "src=" Https://s4.51cto.com/wyfs02/M00/00/D0/wKiom1mdk6ihkQAmAAAUhdjoX-o745.png "style=" float : none; "title=" screenshot from 2017-08-23 22-38-48.png "alt=" Wkiom1mdk6ihkqamaaauhdjox-o745.png "/>650) this.width=650; "src=" Https://s4.51cto.com/wyfs02/M02/9F/80/wKioL1mdk56TXfZHAAATseIwAOw478.png "style=" float : none; "title=" screenshot from 2017-08-23 22-39-10.png "alt=" Wkiol1mdk56txfzhaaatseiwaow478.png "/>15. Queryin

What is a shell script sampleLet's look at an example:#!/bin/shcd ~mkdir Shell_tutcd shell_tutfor (i=0; iExample explanation Line 1th: Specify the script interpreter, here is the interpreter with/bin/sh Line 2nd: Switch to the current user's home directory Line 3rd: Create a directory Shell_tut Lin

.... Now $var can be used .... Here is an example: #!/bin/sh echo "What's your favourite OS?" Select Var in "Linux", "Gnu Hurd" "Free BSD" and "other"; Do Break Done echo "You have selected $var" The following is the result of the script running: What is your favourite OS? 1) Linux 2) Gnu Hurd 3) Free BSD 4) Other #?

What is a shell script, first of all it is a script, and not as a formal programming language, so to speak is that the shell script is a collection of commands.All custom

$name >/dev/nullif [$?-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

What is Bash shell script programming?A: There are multiple shells in Linux, and the default shell for CentOS and Redhat is the bash shell. As for shell scripts, this

Tags: ges vim editor nginx root user Form bash script expec Ash rsyncObjectiveLearn about the knowledge reserves required for Shell script programming:Vi/vim Editor Command VIMRC set to be proficientBasic commands, more than 100 skilledBasic and common Network Service commands to be: NFS, rsync, INotify, Lanmp, Sersync, SSH keyI. Shell scripting concepts and exam

2 3 Do For var2 in 0 5 Do if [ $var 1 -eq 2-a $var 2 -eq 0 ] /c0> Then break 2 Else Echo "$var 1 $var 2" fi Done Done As above, break 2 means to jump out of the outer loop directly. Operation Result:1 01 5Continue commandThe continue command is similar to the break command, with only a little difference, and it does not jump out of all loops and just jumps out of the current loop.To modify the above example: #!/b

The Until loop executes a series of commands until the condition is true. The Until loop and the while loop are just the opposite of the processing mode. The general while loop is better than the until loop, but at some point it is only rare that the until loop is more useful.The Until loop format is:Until Commanddo

# input Check:If [-Z ']; ThenError "Error:you must specify a file, use-h for help"FiFilen= "$"# Rename any. 1,. 2 etc File:For N in 9 8 7 6 5 4 3 2 1; DoIf [-F ' $filen. $n "]; Thenp= ' expr $n + 1 'echo "MV $filen. $n $filen. $p"MV $filen. $n $filen. $pFiDone# Rename the original file:If [-F "$filen"]; Thenecho "MV $filen $filen. 1"MV $filen $filen. 1Fiecho Touch $filenTouch $filenHow does this script work? After detecting a file name provided by the user, we perform a 9 to 1 loop. File 9

The first part of the Linux command lineThe 1th chapter of the first knowledge of Linux she1.1 What is Linux 21.1.1 Deep Dive into Linux kernel 31.1.2 GNU Tools 61.1.3 Linux Desktop Environment 81.2 Linux Release 121.2.1 Core Linux Release 131.2.2 Linux distributions for specific purposes 131.2.3 Linux LiveCD 141.3 Summary 152nd Chapter into the shell2.1 Entering command line 162.1.1 Console Terminal 172.1.

As we all know, PHP (as the current mainstream development language) is a very good dynamic web development language (fast, short development cycle ...). ）。 But only a very small number of people realize that PHP (as the current mainstream development language) can also be very good as the language of writing shell scripts, when PHP (as the current mainstream development language) as the language of writing

1. Linux Scripting Basics1.1 Basic Introduction to grammar1.1.1 StartThe program must start with the following line (must be placed on the first line of the file):#!/bin/shThe symbolic #! is used to tell the system that the parameters behind it are the programs used to execute the file. In this example we use/BIN/SH to execute the program.When you edit a good script, you must also make it executable if you

" fiif [$a-gt $b]then echo "$a GT $b" else echo "A not greater than B" fiif [$a-le $b]then echo ' $a le $b "Else echo" a not less or equal to B "fi Run Result: (with previous edits entered in the content ha)$ sh test.shTotal Value:4A * b:200A% b:0A not equals BA not equals BA not greater than BTen Le 20Well, when you write a script, you can guess what-gt and-le do. Let's look at the system.List of relational operators

echo "Top Ten Disk Space Usage" echo "for $CHECK _directories Directory" For Dir_check in $CHECK _directories Do echo "" echo "The $DIR _check Directory:" Du-s $DIR _check 2>/dev/null | Sort-rn | Sed ' {one, $D; =} ' | Sed ' N; s/\n//' | Gawk ' {printf $ ': "\ T" $ "t" $ "\ n"} ' Done Exit [Email protected]:~/shell/24zhang$ Run:./big_user.shOnly two directories/var/log/home are specified above, and the generated rep

] ~]# Expr 2 * 3expr:syntax errorSecond, let command[[email protected] ~]# let A=2+3[[email protected] ~]# echo $a 5[[email protected] ~]# let A=2-3[[email protected] ~]# Echo $a -1[[email protected] ~]# let A=2*3[[email protected] ~]# echo $a 6[[email protected] ~]# let A=2/3[[email protected] ~]# echo $a 0[[email protected] ~]# b=4[[email protected] ~]# c=2[[email protected] ~]# let a= $b/$c [[email protected] ~]# Echo $a 2When using let, it is gene

Shell Scripting Learning The shell is the command parser that converts the user-entered instruction into a program that the appropriate machine can run.The shell is a program that acts as an interface between a user and a Linux s