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Question

I'm trying to run a query on a remote server from by bash script. Problem is, I have to use single quotes inside of the query which already has surrounding single quotes.

My code:

# note: $line has ` in it, as this is a SQL query
ssh server "mysql --defaults-extra-file=$SQL_CREDS_FILE $R_DB $t -e '$line INTO OUTFILE \"\'\"$DIR/$tbl_count.csv\"\'\" FIELDS TERMINATED BY \"\'\",\"\'\" ENCLOSED BY \"\'\"\"\'\" LINES TERMINATED BY \"\'\"\n\"\'\"'"

The error I'm seeing upon running this code:

bash: -c: line 0: unexpected EOF while looking for matching `"'
bash: -c: line 1: syntax error: unexpected end of file

Example of working MYSQL query:

mysql -u user -pPassword database -e 'select `id`,`title`,`name`,`description`,`icon`,`creation_date` as `created_at`,`mutation_date` as `created_at` from achievement;'

Answer 1

The simplest workaround is to use a context where you don't quote the expression at all.

Using a here document will tie up the standard input of ssh , but in this case it seems acceptable (or perhaps even desirable).

ssh server <<____HERE
# Guessing $R_DB contains "database"
# Guessing $t contains your credentials ...?
# Guessing $DIR contains a directory name
# Guessing $tbl_count contains a file name
# Guessing $line contains your actual query  
mysql "$R_DB" $t -e "${line//\`/\\\`} INTO OUTFILE '$DIR/$tbl_count.csv'
    FIELDS TERMINATED BY ',' ENCLOSED BY '' LINES TERMINATED BY '\n'"
____HERE

The parameter expansion ${line//\\`/\\\\\\`} is a Bash-only feature so this depends on the remote shell being Bash.

Answer 2

After the comment by @KamilCuk it got me thinking about the escape characters and running the code without the SSH.

I have rewritten the code to only contain " or ' which results in:

ssh server "mysql --defaults-extra-file=$SQL_CREDS_FILE $R_DB -e \"$line INTO OUTFILE '$DIR/$tbl_count.csv' FIELDS TERMINATED BY ',' ENCLOSED BY '' LINES TERMINATED BY '\n'\"" < /dev/null

Also removing the ` helped, as anything between that character will be executed as a command.