Question

I expect the answer to this is already here someplace, but I was not able to find it. I’m wasting too much time messing around with this. Best to just ask and move on.

I am trying to create a (bash) shell script which when run will prompt for the name of an alias and the replacement string and then create that alias. So, being not the sharpest tool in the tool-shed, I tried (copied from a blog actually) the code below.

#!/bin/bash
echo "Enter the identifier for the alias (shortcut)"
read SHORTTEXT
echo "Now enter the string which $SHORTTEXT will alias:"
read LONGTEXT
alias $SHORTTEXT='$LONGTEXT'

I put the above code into the file ~/scripts/nojoy.sh, made the file executable, and then tried it out.

myid@myid:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 11.10
Release:    11.10
Codename:   oneiric
myid@myid:~$
myid@myid:~$ . ~/scripts/nojoy.sh 
Enter the identifier for the alias (shortcut)
testit
Now enter the string which testit will alias:
cd ~
myid@myid:~$ alias testit
alias testit='$LONGTEXT'

I then spend more time than I’ll admit to attempting to modify the clearly just plain wrong
alias $SHORTTEXT='$LONGTEXT'
into something which when the script was run would result in creating
alias testit='cd ~'
when the script runs.

I give up. Can someone please just explain to me how to do this so I can get on to doing something else more important than this? (Like cleaning litter boxes maybe?)

---

Update:

I did not expect to have a hard time picking an answer for this. But both answers work, albeit in different ways, and I’m not sure I appreciate whatever underlying subtleties there might be.

Using alias $SHORTTEXT="$LONGTEXT" in my script file together with the input string
find . -name '*.txt'
resulted in
alias test='find . -name '\''*.txt'\'''

Using eval "alias $SHORTTEXT='$LONGTEXT'" resulted in
alias test='find . -name *.txt'

I decided that my naive expectation of what the alias my shell script defined should do boiled down to pure text substitution. That is, if I defined an alias named
example for echo '*.txt' then when I used it I’d expect the result to be *.txt

Using the method in the first answer does this. The second answer does not. So I picked the first answer as closer to what I think I was looking for.

Thanks to all!

Answer 1

What you get is what the single quotes in:

alias $SHORTTEXT='$LONGTEXT'

demand. If you want $LONGTEXT expanded, use:

alias $SHORTTEXT="$LONGTEXT"