How to create an bash alias for the command "cd ~1"

Question

In BASH, I use "pushd . " command to save the current directory on the stack. After issuing this command in couple of different directories, I have multiple directories saved on the stack which I am able to see by issuing command "dirs". For example, the output of "dirs" command in my current bash session is given below -

0 ~/eclipse/src
1 ~/eclipse
2 ~/parboil/src

Now, to switch to 0th directory, I issue a command "cd ~0". I want to create a bash alias command or a function for this command. Something like "xya 0", which will switch to 0th directory on stack. I wrote following function to achieve this -

xya(){
cd ~$1
}

Where "$1" in above function, is the first argument passed to the function "xya".

But, I am getting the following error -

-bash: cd: ~1: No such file or directory

Can you please tell what is going wrong here ?

Answer 1

Generally, bash parsing happens in the following order:

• brace expansion
• tilde expansion
• parameter, variable, arithmetic expansion; command substitution (same phase, left-to-right)
• word splitting
• pathname expansion

Thus, by the time your parameter is expanded, tilde expansion is already finished and will not take place again, without doing something explicit like use of eval.

---

If you know the risks and are willing to accept them, use eval to force parsing to restart at the beginning after the expansion of $1 is complete. The below tries to mitigate the damage should something that isn't eval-safe is passed as an argument:

xya() {
  local cmd
  printf -v cmd 'cd ~%q' "$1"
  eval "$cmd"
}

...or, less cautiously (which is to say that the below trusts your arguments to be eval-safe):

xya() {
  eval "cd ~$1"
}

Answer 2

You can let dirs print the absolute path for you:

xya(){
    cd "$(dirs -${1-0} -l)"
}