This was easy to implement once I found the programmable completion tool by Ian Macdonald. I just added the following section to bash_completion:

[cc lang="bash" tab_size="2"]
# hdfs(1) completion
#
have hadoop &&
_hdfs()
{
local cur prev

COMPREPLY=()
cur=${COMP_WORDS[COMP_CWORD]}
prev=${COMP_WORDS[COMP_CWORD-1]}

if [[ "$prev" == hdfs ]]; then
COMPREPLY=( $( compgen -W ‘-ls -lsr -du -dus -count -mv -cp -rm
-rmr -expunge -put -copyFromLocal -moveToLocal -mkdir -setrep
-touchz -test -stat -tail -chmod -chown -chgrp -help’ — $cur ) )
fi

if [[ "$prev" == -ls ]] || [[ "$prev" == -lsr ]] ||
[[ "$prev" == -du ]] || [[ "$prev" == -dus ]] ||
[[ "$prev" == -cat ]] || [[ "$prev" == -mkdir ]] ||
[[ "$prev" == -put ]] || [[ "$prev" == -rm ]] ||
[[ "$prev" == -rmr ]] || [[ "$prev" == -tail ]] ||
[[ "$prev" == -cp ]]; then
if [[ -z "$cur" ]]; then
COMPREPLY=( $( compgen -W “$( hdfs -ls / 2>-|grep -v ^Found|awk ‘{print $8}’ )” — “$cur” ) )
elif [[ `echo $cur | grep /$` ]]; then
COMPREPLY=( $( compgen -W “$( hdfs -ls $cur 2>-|grep -v ^Found|awk ‘{print $8}’ )” — “$cur” ) )
else
COMPREPLY=( $( compgen -W “$( hdfs -ls $cur* 2>-|grep -v ^Found|awk ‘{print $8}’ )” — “$cur” ) )
fi
fi
} &&
complete -F _hdfs hdfs
[/cc]

I’m sure there are some ways to make the code more elegant, but it is called HackLeaf, after all. This bit of code builds on top of other functions in the script, but the basic idea is pretty simple. cur contains the current word you are typing, so this would be a partial command or partial path. prev contains the previous word. If the previous word is hdfs, then we present the user with valid arguments to hdfs. If the previous word is -ls (or any other command where you want a path/file), then present the user with the possibilities for that path or partial path. HDFS defaults to the user’s home directory if no path is provided, so we override that by presenting the user with the possibilities under “/”. Finally, COMPREPLY returns the possibilities to the user on the command-line.

Be sure to check out some of the other features of bash_completion, particularly ssh and chkconfig.