shell programming

shell script file ex4.sh,Run the script 3 times at the Shell command Terminal to see the results of its operation.① run for the 1th time:. ex4.sh② run for the 2nd time:. ex4.sh /etc/apt/sources.list③ Run for the 3rd time:. ex4.sh /etc/apt/sources.list ex4.shAnalyze the shell script function with the result of running . Reply:What is the function of NL in ①line4-

Functions: functionProgram programming: Code reuse;Modular programming;Structured programming;Consider the code of an independent function as a whole, and take a name for it; a named code snippet, which is a function;Definition and use of functions:Functions can be defined in an interactive environment;A function can be placed in a script file as part of it;Can b

Shell Basics What is a shell? Shell is a command-line interpreter The shell is also a very powerful programming language that can invoke Linux commands directly in the shell How the

statement 3.3 While/for Cycle 4 Some special symbols in the shell 4.1 quotation marks 5 here Document 6 functions in the shell 7 command-line arguments 8 Shell Script Example 8.1 General Programming steps 8.2

scriptCreation of shell scripts:Shell scripts are typically written in the editor (vi vim) and consist of UNIX/LINUX commands, bash shell commands, Program structure control statements, and annotation contentScript start (first line)The first line of a canonical shell script indicates that the program (parser) executes the contents of the script, which is typica

command line parameters: #! /Bin/sh Cp $1 $2 The preceding script accepts two command line parameters. The first is the original file to be copied, and the second is the target file to be copied. the command format for running the script is :. /myscript file1 file2, myscript represents the script file name, command line options can also be passed in this way, such: #! /Bin/sh Cp $1 $2 $3 Run the command in the form of./copy-r sourcedir destdir to execute the preceding script

"Your third parameter is $third" # Sh-x command: single-step debugging display and execution 2. expr command to calculate Integer Variables For example, there must be a space between expr 3 + 5 # "+" Expr $ var1-5 Expr $ var1/$ var2 Expr $ var3 \ * 10 # "*" requires an escape character "\" Complex operations: Expr 'expr 5 + 7'/$ var4 Assign the calculation result to the variable: Var4 = 'expr $ var1/$ var2' Example-expr. Sh #!/bin/bash# A test for expra=10b=20c=30val1=$(expr $a + $b +

Like other advanced programming languages, Shell provides commands used to control program execution processes, including conditional branches and loop structures. You can use these commands to create very complex programs. Unlike traditional languages, Shell is used to specify condition values instead of Boolean operations, but commands and strings. 1. Test comm

#!/bin/ Bashinput () {echo $1}input AAA addition operation function #!/bin/bashsum () {S=$[$1+$2]echo $s}sum 1 2 #!/bin/baship () {ifconfig |grep-a1 "$" |tail-1 |awk ' {print $} ' |awk-f ': ' {print $} '}read-p ' Pleasr input the ETH name: ' emyip= ' IP $e ' echo ' $e address is $ Myip "----------------------------------------------------------------------Shell ArrayArray definition, a pair of parentheses represents an array, the array element is sepa

Shell Introduction The shell is a programming language interpreter, which interprets commands entered from the keyboard, and also explains the sequence of commands stored in the script, which is a file containing a series of commands, and running a script is running each command in the file. You can use a shell sc