Run a for loop using a comma separated bash variable - mongodb

Question

I have a list of collections as a comma seperated variable in Bash like below
list_collection=$collection_1,$collection_2,$collection_2,$collection_4
I want to connect to Mongodb and run some commands on these collections
I have done like below but I am not getting the loop to work
${Mongo_Home}/mongo ${mongo_host}/${mongo_db} -u ${mongo_user} -p ${mongo_password} <<EOF
use ${mongo_db};for i in ${list_collection//,/ }
do
db.${i}.reIndex();
db.${i}.createIndex({
"recon_type":1.0,
"account_name":1.0,
"currency":1.0,
"funds":1.0,
"recon_status":1.0,
"transaction_date":1.0},
{name:"index_def"});
if [ $? -ne 0 ] ; then
echo "Mongo Query to reindex ${i} failed"
exit 200
fi
done
EOF
What wrong AM I doing?
What is the correct way?

Answer 1

It's hard to guess what your desired behavior is from a bunch of code that doesn't exhibit that behavior, but to take a shot at it, the following will run mongo once per item in list_collection, with a different heredoc each time:
#!/usr/bin/env bash
# read your string into a single array
IFS=, read -r -a listItems <<<"$list_collection"
# iterate over items in that array
for i in "${listItems[#]}"; do
{ # this brace group lets the redirection apply to the whole complex command
"${Mongo_Home}/mongo" "${mongo_host}/${mongo_db}" \
-u "${mongo_user}" -p "${mongo_password}" ||
{ echo "Mongo query to reindex $i failed" >&2; exit 200; }
} <<EOF
use ${mongo_db};
db.${i}.reIndex();
db.${i}.createIndex({
"recon_type":1.0,
"account_name":1.0,
"currency":1.0,
"funds":1.0,
"recon_status":1.0,
"transaction_date":1.0
}, {name:"index_def"});
EOF
done
Alternately, to run mongo just once (but lose the ability to tell which index a failure happened for) might look like:
#!/usr/bin/env bash
# read your string into a single array
IFS=, read -r -a listItems <<<"$list_collection"
buildMongoCommand() {
printf '%s\n' "use $mongo_db;"
for i in "${listItems[#]}"; do
cat <<EOF
db.${i}.reIndex();
db.${i}.createIndex({
"recon_type":1.0,
"account_name":1.0,
"currency":1.0,
"funds":1.0,
"recon_status":1.0,
"transaction_date":1.0
}, {name:"index_def"});
EOF
done
}
"${Mongo_Home}/mongo" "${mongo_host}/${mongo_db}" \
-u "${mongo_user}" -p "${mongo_password}" \
< <(buildMongoCommand) \
|| { echo "Mongo query failed" >&2; exit 200; }