sourced script won't execute alias after command expansion

NeoLux · 03-07-2015, 03:18 PM

Hi... So I get that you have to source a shell script to execute any currently defined aliases within it, effectively executing commands as if you had typed them yourself, but well, instead of explaining I'll just show you...

Code:

 
:> alias hi="echo hello"
:> touch test.sh
:> chmod 777 test.sh # *write some code
:> source ./test.sh
hello
hi DAD
bash: hi: command not found

---- test.sh ----

Code:

#!/bin/bash

hi
echo $(echo "hi MOM" | sed "s:MOM:DAD:")
$(echo "hi MOM" | sed "s:MOM:DAD:")

so yeah, I considered maybe it's another layer of being a "subshell" in those
$()'s, but if that were the case how would you source an expanded command?
(sorry if I'm misinterpreting the issue)
Basically, is there a workaround ?
thx to anyone who looks and gives me a reply.
-cheers & God speed !

teckk · 03-07-2015, 04:35 PM

Not sure what you are doing. Does this help?

Code:

#! /usr/bin/env bash

hi="hello"

echo ""$hi""
echo "hi"

echo ""$hi" MOM" | sed "s:MOM:DAD:"
echo "hi MOM" | sed "s:MOM:DAD:"

NeoLux · 03-07-2015, 05:07 PM

no, this is specificall something with aliases but thank you for the reply all the same

I was looking and I think maybe the answer for me is "eval"

Code:

:> alias hi="echo hello"
:> hi
hello
:> echo $(echo hi)
hi
:> $(echo hi)
bash: hi: command not found
:> eval $(echo hi)
hello

That's what I was trying to do, I wanted to executed it after I had expanded it to the real command.

in this example it doesn't change anything, but for what I was doing I was expanding it to a new command that I didn't know in advance.

ntubski · 03-07-2015, 08:32 PM

If you use a function instead of an alias it works:

Code:

~/tmp$ cat test.sh 
#!/bin/bash

hi
echo $(echo "hi MOM" | sed "s:MOM:DAD:")
$(echo "hi MOM" | sed "s:MOM:DAD:")

hi-fun
echo $(echo "hi-fun MOM" | sed "s:MOM:DAD:")
$(echo "hi-fun MOM" | sed "s:MOM:DAD:")
~/tmp$ alias hi='echo hello'
~/tmp$ hi-fun() { echo hello "$@" ; }
~/tmp$ source test.sh 
hello
hi DAD
bash: hi: command not found
hello
hi-fun DAD
hello DAD

NeoLux · 03-07-2015, 11:05 PM

Thx, although my concern was for making this work with an alias, it'll be nice to keep the function alternative in mind.