if [ false ]; then echo "HELP"; fi if test false; then echo "HELP"; fi 两个都是检查参数 "false" 是不是非空的,所以上面两个语句都会输出 HELP。 if 语句的语法是: if COMMANDS then <COMMANDS> elif <COMMANDS> # optional then <COMMANDS> else <COMMANDS> # optional fi # required 再次强...
then <COMMANDS> else <COMMANDS> # optional fi # required 再次强调,[是一个命令,它同其它常规的命令一样接受参数。if 是一个复合命令,它包含其它命令,[并不是 if 语法中的一部分。 如果你想根据 grep 命令的结果来做事情,你不需要把 grep 放到 [里面,只需要在 if 后面紧跟 grep 即可: ifgrep -q foo...
ifCOMMANDSthen<COMMANDS>elif<COMMANDS># optional then<COMMANDS>else<COMMANDS># optional fi # required 再次强调,[是一个命令,它同其它常规的命令一样接受参数。if 是一个复合命令,它包含其它命令,[并不是 if 语法中的一部分。 如果你想根据 grep 命令的结果来做事情,你不需要把 grep 放到 [里面,只需要在...
NOTE:You can tie multiple commands using bash operators to achieve the best result. For example, you can allow sleep to execute only if ping and echo execute successfully. $ ping -c 1 linuxhint.com && echo "Success" || sleep 100; In the example above, if either ping or echo fails, ...
最基本的结构化命令就是if-then语句。if-then语句有如下格式。 if command then commands fi if command1 then command set 1 elif command2 then command set 2 elif command3 then command set 3 elif command4 then command set 4 fi 记住,在elif语句中,紧跟其后的else语句属于elif代码块。它们并不属于之前...
Running multiple commands in one line in shell; &&表示只有前一条语句执行成功,才执行下一条命令;&& operator to execute the next command only if the previous one succeeded ;表示顺序执行即可。 &:后台进程(background); If a command is terminated by the control operator ‘&’, the shell executes...
Next, we’ll cover some of the basics of Bash scripting. You’ll learn how to create a script, use variables, and work with conditional statements, such as “if” and “if else”. You’ll also learn how to use a case statement, which is a way to control the flow of execution bas...
You can use this to create multiple directories at once within your current directory.mkdir 1stDirectory 2ndDirectory 3rdDirectoryYou can also use this to create parent directories at the same time with the -p (or --parents) flag. For instance, if you wanted a directory named 'project1' in...
Your code for each command is kept in a separate file, and can be merged again if you change it (example). Features Bashly is responsible for: Generating asingle, standalone bash script. Generating ahuman readable, shellcheck-compliant and shfmt-compliant script. ...
if: Used for conditional statements, where you need to execute certain commands only if a specified condition is true. else: Works in conjunction with the"if"keyword to specify a block of commands to be executed if the condition in the"if"statement is false. ...