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Can You Index an array with an integer in Bash?
No. You can only index a simple array with an integer in bash. Associative arrays (introduced in bash 4) can be indexed by strings. They don’t, however, provided for the type of reverse lookup you are asking for, without a specially constructed associative array.
How to get the index of an array?
The while loop is an interesting method for iteration, with cutoff, with the purpose of generating an index for an array value, the body of the loop contains only a colon for null operation. The important part is the iteration of i until a match, or past the possible matches.
How are arrays passed as parameters in Bash?
So, if it had been done right, then the following example would show how the usefulness of arrays in bash could be substantially better: Then, arrays could use the assignment operator, and be passed by value to functions and even other shell scripts. Easily stored by outputting to a file, and easily loaded from a file into a script.
How to assign a value to an array in Bash?
Especially when you consider that $ {array [0]} has no meaning and evaluates to the empty string if the array type is associative. Assigning an array takes the form array= (value1 valueN) where value has the syntax [subscript]=string, thereby assigning a value directly to a particular index in the array.
How to pad a sequence of integers in Bash?
More generally, bash has printf as a built-in so you can pad output with zeroes as follows: You can use the -v flag to store the output in another variable: Notice that printf supports a slightly different format to seq so you need to use %05d instead of %05g.
How to exit submenu in Unix and Linux?
Check it out: If a user selects 1 from the main menu, the submenu function kicks off. If the user then types “4” and hits enter, it just sits there. If they hit enter again, THEN it pops back to the main menu. Not sure what I’m missing, I feel it’s something simple.
How to check if an element is set in an array?
To check if the element is set (applies to both indexed and associative array) This answer is actually adapted from the answers for this SO question: How to tell if a string is not defined in a bash shell script?
How to check if bar and Baz are set in Bash?
This will show that both foo [bar] and foo [baz] are set (even though the latter is set to an empty value) and foo [quux] is not. From version 4.2 of bash (and newer), there is a new -v option to built-in test command.