including if, else, and elif. Then we'll look at a few of the "primary" operators you can leverage in a conditional statement such as = for string equality, -eq for numeric equality, and -e to check if a file exists. After that, we'll use conditional statements...
not equals:-ne is empty:-z if[[1-eq1]];if[[-z$USER]]; Elif if[[-z$USER]];thenecho"user is empty"elif[[1-eq1]];thenecho"1==1"elseecho"false"fi Ternary [[$USER='username']]&&echo"yes"||echo"no" Exp: check_status(){## Get HTTP status codelocalstatus=$(curl-ILs$1|...
如果if结构使用的不是test命令,而是普通命令,比如上一节的((...))算术运算,或者test命令与普通命令混用,那么可以使用 Bash 的命令控制操作符&&(AND)和||(OR),进行多个命令的逻辑运算。$ command1 && command2 $ command1 || command2对于&&操作符,先执行command1,只有command1执行成功后, 才会执行command2。
bash command if a string is not empty examples of the check when DiskInternals can help you Are you ready? Let's read! Variables that are set and not empty A variable is either defined or not defined. However, when a variable is defined but has no value, then the variable is “Not ...
Pay attention toecho $(( $1 * $(factorial $(( $1 -1 ))) )). The code is calling the function itself with 1 value less. The process goes in until the value equals 1. So if you run the script with argument 5, it will eventually result in 5 * 4 * 3 * 2 *1. ...
Below is an simple example of if else loop using string comparison. It will check if the varibale “total” has a value assigned equal to 100. #!/bin/bash total=100 if [ $total -eq 100 ]; then echo "total is equal to 100" ...
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Discussion $-is a string listing of all the current shell option flags.It will containiif the shell is interactive. You may also see code like the following (this will work, but the solution inExample 1-1is the preferred method): if...
The if stanza sets $OPT to the contents of $OPTARG before the first equals sign (bravo in our example) and then removes that from the beginning of $OPTARG (yielding =foo in this step, or an empty string if there is no =). Finally, we strip the argument's leading =. At this ...
Bash Equals-Separated (e.g., --option=argument) (without getopt▼显示)我要为-x y而不是-x=y做什么改变?没有答案提到增强型getopt。最热门的答案是误导性的:它忽略了-?vfd样式的短选项(由op请求),位置参数后的选项(也由op请求),并且忽略了解析错误。而是:从...