Bash interprets && as an argument
bash, linux
Solution
Variables are not meant to store scripting. Store code in functions, not variables.
$ test() { echo hello && echo world; }
$ test
hello
world
The reason `$test` doesn't work is because unquoted variable expansions are only subjected to two of bash's many phases of parsing:
- Word splitting
- Globbing
That means it will split apart `$test` into separate words, which is why it recognizes the `echo` command. It will also expand wildcards AKA globs. Those are the only two bits of parsing it does, though. It doesn't look for symbols like `&&`, `|`, or `;`.
I don't recommend it, but you can get bash to execute your string with `bash -c "$test"` or `eval "$test"`. These are bad habits that you should avoid unless absolutely necessary. Functions are much better than hacks with `eval`, and they don't open up potential security holes by allowing arbitrary code execution.
Problem
Observe the following ``` [admin@myVM ~]$ test="echo hello && echo world" [admin@myVM ~]$ $test hello && echo world [admin@myVM ~]$ echo hello && echo world hello world ``` It seems that if you place && into a bash variable and execute it as a command, bash interprets && as a string argument. Does anyone know how to alter this behavior? That is to say, does anyone know how to tell bash “I want to execute double ampersand”.