Can't exec an alias or function [closed] - bash

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I have an alias that I would like to be able to call into with exec but I'm not sure how to make it work. The example is simplified but I think enough to highlight the issue. Changing the alias to a function doesn't work either. Calling the alias/function directly does work, just not when using exec.
The command I am using is,
alias myalias="ls -lah /tmp"
exec myalias
But it fails with something similar to the following,
bash: exec: myalias: not found
Is it just not possible to do this using exec?

Answer 1

You don't have any functions or aliases in your example, but if you did have an alias, you could have aliased exec itself to exec it:
#!/bin/bash -i
# Define an alias
alias myalias="ls -lah /tmp"
# Allow `exec` to work for aliases
alias exec='exec '
# This now works as expected
exec myalias
Here's man bash for why this works:
Aliases allow a string to be substituted for a word when it is used as
the first word of a simple command. [...]
If the last character of the alias value is a blank, then the next command word following the alias is also checked for alias expansion.

Answer 2

An alias definition:
$ alias myalias='ls -lah /tmp'
Invoking the alias:
$ myalias
total 36M
drwxrwxrwt+ 1 myuser None 0 Nov 30 16:01 ./
drwxr-xr-x+ 1 myuser None 0 Nov 6 11:29 ../
-rw-r--r-- 1 myuser mygroup 0 Oct 10 11:31 a
-rw-r--r-- 1 myuser mygroup 0 Oct 10 11:31 b
-rw-r--r-- 1 myuser mygroup 0 Oct 10 11:31 c
-rw-r--r-- 1 myuser mygroup 0 Oct 10 11:31 d
-rw-r--r-- 1 myuser mygroup 36M Jun 6 17:29 giga.txt
drwx------+ 1 myuser mygroup 0 Mar 8 2020 runtime-makaakd/
drwx------+ 1 myuser mygroup 0 Nov 8 16:10 tmp.8yl3CJgSn2/
-rw------- 1 myuser mygroup 66 Oct 14 21:49 tmp.BeEvxDpHGr
... snip ...
As is (assigning string to a variable):
$ myalias="ls -lah /tmp"
'Running' the variable:
$ ${myalias}
total 36M
drwxrwxrwt+ 1 myuser None 0 Nov 30 16:01 ./
drwxr-xr-x+ 1 myuser None 0 Nov 6 11:29 ../
-rw-r--r-- 1 myuser mygroup 0 Oct 10 11:31 a
-rw-r--r-- 1 myuser mygroup 0 Oct 10 11:31 b
-rw-r--r-- 1 myuser mygroup 0 Oct 10 11:31 c
-rw-r--r-- 1 myuser mygroup 0 Oct 10 11:31 d
-rw-r--r-- 1 myuser mygroup 36M Jun 6 17:29 giga.txt
drwx------+ 1 myuser mygroup 0 Mar 8 2020 runtime-makaakd/
drwx------+ 1 myuser mygroup 0 Nov 8 16:10 tmp.8yl3CJgSn2/
-rw------- 1 myuser mygroup 66 Oct 14 21:49 tmp.BeEvxDpHGr
... snip ...