2023年6月8日 · When the shell sees &&, it expects to find a command on both sides of it, not inside a command. Also, as was mentioned previously, && is used between commands. We can use logical operators inside [], but we should use an option -a for AND and -o for OR.

打开文本编辑器 (可以使用 vi/vim 命令来创建文件)，新建一个文件 test.sh，扩展名为 sh（sh代表shell），扩展名并不影响脚本执行，见名知意就好，如果你用 php 写 shell 脚本，扩展名就用 php 好了。 输入一些代码，第一行一般是这样： echo "Hello World !" #! 是一个约定的标记，它告诉系统这个脚本需要什么解释器来执行，即使用哪一种 Shell。 echo 命令用于向窗口输出文本。 1 …

2022年8月3日 · We use if-else in shell scripts when we wish to evaluate a condition, then decide to execute one set between two or more sets of statements using the result. This essentially allows us to choose a response to the result which our conditional expression evaluates to.

2024年11月27日 · Though not very frequently used, it is an extremely powerful operator that enables us to match string patterns using regular expressions. This article goes into the practical application of the =~ operator in Bash. The =~ operator …

2020年2月27日 · Conditional Statements: There are total 5 conditional statements which can be used in bash programming. if..then..else..if..then..fi..fi.. (Nested if) Their description with syntax is as follows: This block will process if specified condition is true. statement. If specified condition is not true in if part then else part will be execute.

Bash, short for Bourne Again Shell, is an open-source command-line shell interpreter and scripting language. It interprets user-entered commands, either interactively or from a script file. It serves as an interface to call commands, enabling system function calls.

Bash uses the value of the variable formed from the rest of parameter as the name of the variable; this variable is then expanded and that value is used in the rest of the substitution, rather than the value of parameter itself. This is known as indirect expansion. …(exceptions)…

2018年2月26日 · In the bash shell, the entire script, (i.e. from for to done inclusive), can be simplified to: GLOBIGNORE=even:odd ; printf "%s\n" * Another bash method: shopt -s extglob # only needs to be done once, if not set already. printf "%s\n" !(odd|even)

2022年6月29日 · For the shell to execute a script, the script must have the executable file permission set. Without this, your script is just a text file. With it, it's still a text file, but the shell …

2022年11月14日 · When you are using an if statement and you want to add another condition, the syntax is as follows: statement. else do this by default. fi. Let's see an example where we want to find if the first number is greater or smaller than the second one. Here, if [ $a -lt $b ] evaluates to false, which causes the else part of the code to run. Output: