How do I refer to a variable in bash?
Indirect referencing in Bash is a multi-step process. First, take the name of a variable: varname. Then, reference it: $varname. Then, reference the reference: $$varname.
How do I echo a variable in Bash?
Now, using the echo command we can simply display its value on the terminal as follows:
- $ var_a=100. $ echo $var_a.
- $ var_b=” bash programming echo variable” $ echo $var_b.
- $ var_A=”hellofriends” $ var_B=50. $ echo $var_A$var_B.
- $ var1=$(date) $ var2=$(hostname) $ echo “the date is $var1 @ computer name is $var2”
How to reference a variable in bash based on another variable?
How can I reference a variable in bash based on another variable? Let me setup the example: But this does not work. If you shell supports the $ {!varname} form of indirect references, you can do (as suggested by @Barmar): That said, using eval has some risks associated with it, see this link for more discussion.
How to assign a value to another variable?
You can assign a value to a variable using simple assignment using a value from another variable like so: #!/usr/bin/bash #variable one a=”one” echo “Variable a is $a” #variable two with a’s variable b=”$a” echo “Variable b is $b” #change a a=”two” echo “Variable a is $a” echo “Variable b is $b”.
When to use a variable reference inside another variable?
In older shells, including ksh88 and pdksh, your only recourse when you have a variable containing another variable name and want to use the value of this variable eval, as explained by Bruce Ediger. This solution works in any Bourne/POSIX shell. This is the best method here: it’s simpler and more portable.
Can you make myVar a nameref in Bash?
Unfortunately the method differs between ksh, bash and zsh. In mksh ≥R39b, you can make myvar a nameref: This doesn’t work in ATT ksh93 because it doesn’t support namerefs to positional parameters. In the case where you have a variable containing a variable name, you can use this method.