Tab Completion for Bash and Zsh

Suppose you have files structured as follows:

.
└── manifests
    ├── abc123.manifest
    └── xyz456.manifest

You want to define a bash command mytool that can achieve the follows:

$ mytool <TAB>
abc123 xyz456

$ mytool 12<TAB>
abc123

zsh

If you are an oh-my-zsh user, this can be accomplished by adding the following lines into ~/.zshrc:

# The actual tool that passes the argument to a python script
mytool()
{
    python ~/mytool.py $@
}

# The completion function that helps user quickly input the arguments
_mytool() {
  # zsh completion variable
  local state

  # separate arguments into different groups
  _arguments \
    '1: :->exp'\
    '*: :->others'

  # Take the basename of files in $FOLDER and ends with $FILEEXT
  FOLDER="$PWD/manifests"
  FILEEXT=".manifest"

  local files=()
  for f in $FOLDER/*$FILEEXT; do
      files+=("${${f/$FILEEXT/}/$FOLDER\/}");
  done

  # tab completion only for the first argument
  case $state in
      (exp) _arguments '1:profiles:( $files )' ;;
        (*) compadd "$@" ''
  esac
}
compdef _mytool mytool

bash

tbd.