mongorestore too many open files error workaround with per collection restore

mongorestore-per-collection.sh

#!/bin/bash

if [ $# -eq 0 ]; then
    echo "usage: `basename $0` pathToDb [dbName]"
    exit 1
fi

pathToDb=$1

if [ $# -eq 1 ]; then
    # TODO: use only the depth-most folder name as database name when not provided
    database=$pathToDb
else
    database=$2
fi

echo "# FYI: system limits"
echo "> ulimit -a"
ulimit -a
# A file named `.imported-collections` will be created.
# Use the command `cat .imported_collections | xargs rm` before rerunning the script
# it an error occurs
# echo "# Dropping database..."
# echo "> mongo $database --eval \"db.dropDatabase();\""
# mongo $database --eval "db.dropDatabase();"

for file in $( ls "$pathToDb/" | grep -iE \.bson$ | grep -v system ); do
    collection=$( echo $file | cut -d'.' -f1 )
    echo "> mongorestore --noIndexRestore --db $database --collection \"$collection\" \"$pathToDb/$file\""
    mongorestore --noIndexRestore --db $database --collection "$collection" "$pathToDb/$file"
    exitCode=$?
    if [ $exitCode -ne 0 ]; then
        # the hard way - restart the server and re-attempt importing this collection
        # Only valid for MacOS X, mongodb 3.2 installed with homebrew.
        echo "# ERROR: process excited with code: $exitCode"
        if [ -e "$pathToDb/$file" ]; then
            echo "# Restarting mongo..."
            echo "> brew services restart mongodb@3.2"
            brew services restart mongodb@3.2
            echo "# Waiting a bit for server to be back up..."
            echo "> sleep 10"
            sleep 10
            echo "# Erasing collection data"
            echo "> mongo $database --eval \"db['$collection'].remove({});\""
            mongo $database --eval "db['$collection'].remove({});"
            echo "# Retrying collection import..."
            echo "> mongorestore --noIndexRestore --db $database --collection \"$collection\" \"$pathToDb/$file\""
            mongorestore --noIndexRestore --db $database --collection "$collection" "$pathToDb/$file"
            echo "$pathToDb/$file" >> .imported-collections
        else
            echo "# File $pathToDb/$file doesn't seem to exist."
        fi
    else
        echo "$pathToDb/$file" >> .imported-collections
    fi
done