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How to combine and or condition in bash script?
That is: abort, if either more than 1 argument is given OR if the single argument given does NOT equal one of the acceptable values. Note the ! to negate the expression in parentheses and the use of the POSIX-compliant form of the string equality operator, = (rather than == ).
When to use$ ( command ) in bash script?
From the bash variables tutorial, you know that $ (command) syntax is used for command substitution and it gives you the output of the command. The condition $ (whoami) = ‘root’ will be true only if you are logged in as the root user. Don’t believe me?
When to use the else statement in Bash?
Using else if statement in bash You can use an elif (else-if) statement whenever you want to test more than one expression (condition) at the same time. For example, the following age.sh bash script takes your age as an argument and will output a meaningful message that corresponds to your age:
How to run a while function in Bash?
Open up mcedit and copy-paste your while function in it. Then save and add the correct rights to run your script. copy-paste your while code (don’t forget the shebang: #!/usr/bin/env bash) Click “ Quit” on the bottom right corner and name your script something like while.sh. Test yourself #1 – aka.
Which is an example of a conditional expression in Bash?
Script checks the user who is executing and throws the error. The following script, allows you to execute the oracle installer script only if the user who is executing is non root. In this example the output of the command whoami is compared with the word “root”.
How to test more than one conditional statement?
The conditional expression in the above example reads as: if it is not true that 1 is equal to 0, then… We can test more than one conditional expression at once, using && to require that two conditions that both must be true. Or, using || to require that either one (or both) of the conditions must be true.
What’s the if statement in the Bash shell?
The following Bash shell script code-snippet gets the filename with its absolute path, and checks if the file exists or not and it throws the appropriate information. Refer to our previous article to understand the various bash if statement types.