if[[ -e file_a ]];thenecho file_a exists elif[[ -e file_b ]];thenecho file_b existselseecho none exists fi 这里-e的意思是假如文件存在则为真,否则为假。其他的判断条件有 -v varname True if the shell variable varname is set (has been assigned a value). -z string True if the ...
If avariable starts with a number, then placing an underscore anywhere will have no meaning and considered illegal, as covered in the previous section: $123_var_name=“Welcome to LinuxHint” You can see that the variable is now inwhite colorcompared to the blue in other bash scripts and t...
$ mintty--helpUsage:mintty[OPTION]...[PROGRAM[ARG]...|-]Start anewterminalsession running the specified program or the user's shell.If a dash is given insteadofa program,invoke the shellasa login shell.Options:-c,--configFILELoad specified config file-e,--exec Treat remaining argumentsast...
You can assign data to a variable using the equals sign (=). The data you store in a variable can either be a string or a number. Let’s create a variable now on the command line: chapter_number=5 The variable name is on the left hand side of the equals sign, and the data whic...
If a dash is given instead of a program, invoke the shell as a login shell. Options: -c, --config FILE Load specified config file -e, --exec Treat remaining arguments as the command to execute -h, --hold never|start|error|always Keep window open after command finishes -i, --icon ...
with $0. 译:-c选项的作用是,读取后面字符串的内容做为命令来执行。如果字符串后面还有参数,这些参数可以通过$0/$1...的方式被字符串里的命令引用(举例:执行bash -c 'echo $1 $0' shen 申 ;输出:申 shen)-i If the -i option is present, the shell is interactive. ...
$variable是要检查的变量。 pattern1,pattern2等是匹配模式。 commands1,commands2等是匹配成功后要执行的命令。 *是通配符,用于匹配所有未被前面的模式捕获的情况。 esac是case的结束标记。 优势 可读性:相比于多个if-else语句,case语句更加直观和易于阅读。
else echo "The variable is equal or less than 10." fi Copy If you run the code and enter a number, the script will print a different message based on whether the number is greater or less/equal to 10. if...elif...else Statement The Bash if...elif...else statement takes the fo...
the Bashcanautomatically converted according to certain operations (e.g. arithmetic) variable to the appropriate type. To write a variable and fill it with a value, pleaseVARIABLE=VALUE, making sure that it does not contain spaces. Here is an example showing how to create variables in Bash: ...
if [[ $VAL -lt 20 ]] then echo "The value is less than 20." fi Here, the condition is[ $VAL -lt 20 ]which checks if variable$VALis less than 20. Save this code into a file with.shextension, such asmyscript.sh, and execute by using the following command. ...