Came across this piece of code:

for entry in $(echo $tmp | tr ';' '\n')
do
echo $entry
  rproj="${entry%%,*}"
  rhash="${entry##*,}"
  remoteproj[$rproj]=$rhash
done

So I do understand that initially ';' is converted to new line so that all entries in the file are on a separate line. However, I am seeing this for the first time:

rproj="${entry%%,*}"
rhash="${entry##*,}"

I do understand that this is taking everything before ',' and after comma ',' . But, is this more efficient than split? Also, if someone please explain the syntax because I am unable to relate this to regular expression or bash syntax.

These are string manipulation operators.

${string##substring}

Deletes longest match of $substring from front of $string.

Meaning it will remove everything before the first comma, including it

${string%%substring}

Deletes longest match of $substring from back of $string.

Meaning it will remove everything after the last comma, including it

Btw, I would use the internal field separator instead of the tr command:

IFS=';'
for entry in $tmp ; do
    echo $entry
    rproj="${entry%%,*}"
    rhash="${entry##*,}"
    remoteproj[$rproj]=$rhash
done
unset IFS

Like this.