A Shell script usually needs to test if a command succeeds or a condition is met. In Bash, this test can be done with a Bash if statement. As with any other programming language, Bash comes with conditional expressions that allow you to test for conditions and alter the control flow if ...
Bash, short for "Bourne Again SHell," is a powerful scripting language used in Unix-based operating systems. One of the fundamental constructs in Bash programming is the if statement. The if statement allows you to control the flow of your script based on specific conditions. In this article,...
In this example, the script first checks if ‘a’ is greater than ‘b’. If it’s not, it moves on to the ‘elif’ statement to check if ‘a’ is greater than ‘c’. If neither condition is met, it executes the ‘else’ statement, which in this case, prints ‘a is not greate...
if [ -z "$TEST_VAR" ] then echo "Environment variable TEST_VAR is not set." usage fi Note the following about this script: The statementCALLER=`basename $0`is used to get the name of the script being run. In that way, you do not need to hard-code the script name in the script...
If an error occurs when executing the file, please continue to set the executable permissions for the script file you just wrote by entering the following: chmod +x hello.sh If you followed this example, you have just created a file containing multiple Bash commands. The Bash interpreter will...
if [ $# -gt 0 ]; then echo "has arguments" else echo "don't have arguments" fi 1. 2. 3. 4. 5. 参考: https://wiki.jikexueyuan.com/project/shell-tutorial/shell-if-else-statement.html http:///a_8629 https://www.jb51.net/article/56553.htm ...
1. 创建脚本文件:使用文本编辑器(如vi或nano)创建一个新的文件,例如script.sh。确保文件拓展名为.sh。 2. 添加shebang行:在脚本文件的第一行添加shebang行,指示脚本用哪个shell来运行。常用的是#!/bin/bash。 3. 添加命令:在脚本文件中添加要执行的Linux命令。每个命令占一行,并且可以使用任何Linux命令、参数...
Check to see if a variable is empty or not Create a new bash file, named, and enter the script below. The script above stores the first command-line argument in a variable and then tests the argument in the next statement. This script will print the first argument because it is not em...
-ne 不等于,如:if [ "a"−ne"b" ] -gt 大于,如:if [ "a"−gt"b" ] -ge 大于等于,如:if [ "a"−ge"b" ] -lt 小于,如:if [ "a"−lt"b" ] -le 小于等于,如:if [ "a"−le"b" ] < 小于(需要双括号),如:(("a"<"b")) ...
if [[ $stringItem = "hello" ]] then echo "The string does match but is not case sensitive." else echo "The string does not match because of the capitalized H." fi 你将得到以下三行: [zexcon@fedora ~]$ ./learnToScript.sh The string is an exact match. The string does not match ...