循环 bash 别名并在脚本中运行命令

Question

I'm trying to create a bash script which has a list of aliases and run them in my script. (This is just a simplified example, but it explains the situation).

What should happen is I loop over my aliases and the script executes them one by one.

alias_list.sh

#!/bin/bash

alias al1="ls"
alias al2="ls ."
alias al3="ls .."

test_alias_loop.sh

#!/bin/bash -i

# Expand aliases
shopt -s expand_aliases
source ~/Documents/test_ssh_bash/scripts/alias_list.sh

# Exists just to get a list of aliases, proper version gets aliases from bash command
aliases=$(printf "al1\nal2\nal3\n\n")

for ssh_alias in $aliases; do
  echo "$ssh_alias"
  $ssh_alias
done

This is what I get for the first command./test_alias_loop.sh: line 12: al1: command not found

But, when I just do

al1

The command runs and I get an ls of my current directory.

How can I loop over a list of alias commands and actually run them in my script?

Answer 1

If the intent is to check to make sure the aliases are valid, then piping them to bash after processing seems to work.

$alias ls1='ls 1'
$alias ls2='ls 2'
$alias ls3='ls 3'

$alias |
 while read -r line ; do
   echo "$line" |
   perl -pe 's/.*?=//' |
   xargs
 done | bash

Gives:

ls: cannot access '1': No such file or directory
ls: cannot access '2': No such file or directory
ls: cannot access '3': No such file or directory

Answer 2

Your problem can be simplified to this example:

alias xx=echo
foo=xx; 
$foo text. 

You will get bash: xx: command not found . It seems that commands, after variable expansion, are not treated as possible aliases anymore. This can be explained from the following sentence taken from the bash man page:

Aliases allow a string to be substituted for a word when it is used as the
first word of a simple command.... The first word of each simple command,  if
unquoted,  is  checked to see if it has an alias.

While it does not explicitly say so, I take it that the first word in the command is tested before any other substitution.

But even if you find a way around this problem, your script would not work, because - as the man page says -:

 Aliases are not expanded when the shell is not interactive, unless the 
 expand_aliases shell option is set using shopt.

So to use aliases in your script, you have to explicitly turn on this feature.