使用当前路径中的值创建外壳别名

Question

I want to create a shell alias which would run

command ew --constantswitch --anotherconstantswitch <name>

Now the value name needs to be extracted from the current path. the current path looks like this

[username@path-to-shell-xxxxxxxx]/path/to/directory/with/name%

How can I create an alias such that when I run aliasX it will

1. Extract the name from current path (which is last value of the prompt)
2. Add this path to the command above and execute.

Answer 1

An alias may not be competent for the job, but a function surely do. Try this code:

myfunc() {
  command ew --constantswitch --anotherconstantswitch "${PWD##*/}"
}

The trick is ${PWD##*/} . You know the automatic variable $PWD is exactly what you get when you run pwd , as well as Bash's builtin string substitution ${var##pattern} that removes pattern from the left of the variable with maximum match. So ${PWD##*/} removes everything except the name after the last slash, which as you described is what you're looking for.

In practice, a function is more versatile than an alias. If you still need to add extra arguments to the command, append "$@" to the end of the command inside the function, so any argument that you pass to the function will be forwarded to the command.

Answer 2

Since you're not trying to do anything involving arguments, an alias is actually possible:

alias aliasX='echo "${PWD##*/}"'

This will print the current directory name when you use aliasX . Or, using your example:

alias aliasX='command ew --constantswitch --anotherconstantswitch "${PWD##*/}"'

Notice that the alias must be in single quotes or $PWD will expand when you define it instead of when you use it.

For anything slightly more complex, you should use a function instead of an alias, as shown in iBug's answer .