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@ -48,7 +48,7 @@ See something incorrectly described, buggy or outright wrong? Open an issue or s
* [Loop over the contents of a file](#loop-over-the-contents-of-a-file)
* [Loop over files and directories](#loop-over-files-and-directories)
* [VARIABLES](#variables)
* [Name a variable based on another variable](#name-a-variable-based-on-another-variable)
* [Name and access a variable based on another variable](#name-and-access-a-variable-based-on-another-variable)
* [ESCAPE SEQUENCES](#escape-sequences)
* [Text Colors](#text-colors)
* [Text Attributes](#text-attributes)
@ -679,10 +679,34 @@ done
## Name and access a variable based on another variable
### Set the dynamic part of the variable name
```shell
$ var="world"
```
#### Option [1]: Set the variable using export
**Warning:** Actually exports the variable, it will be inherited by called programs. Remember to unset.
```shell
$ export "hello_$var=value"
```
#### Option [2]: Set the variable using eval
**Warning:** Does not export the variables, but is more dangerous than using export, as eval can execute arbitrary commands (try with `var="=;echo pwned;_"`). Remember to sanitize any data to only have alphanumerals and underscores.
```shell
$ eval "hello_$var=value"
$ eval printf '%s\n' "\$hello_$var"
```
### Access the variable in a command
**NOTE:** The entire sequence is interpreted an extra time by the shell when calling eval. Note the double-escaping in the printf format.
```shell
$ eval printf '%s\\n' "\$hello_$var"
value
```