Escape quotes correctly for looping over nested ssh commands

$ for server in $(cat servers); do echo $server $(ssh -A user@bastion "ssh -q -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no $server \"/bin/bash -c \\\"which mysqldump\\\"\" "); done

Output:

foo-2 /usr/bin/mysqldump

bar-4 /usr/bin/mysqldump

baz-12 /usr/bin/mysqldump

qux-3 /usr/bin/mysqldump

quxx-4 /usr/bin/mysqldump

MySQL explain plan cheat sheet

Explanation of explain output:

• select_type: SIMPLE/SUBQUERY/UNION/DERIVED
• partitions: NULL ??
• type: (from worst to the best): ALL, index, range, ref, eq_ref, const, system
• possible_keys: food,bar,baz,id (good)
• key: foo(good)
• key_len: 334 ??
• ref: const,const,const ??
• rows: 1 (lower is better. must be less than total rows)
• filtered: 100.00 (lower is better, but only used if there's a join)
• Extra: NULL

Bad extra values:

• using where
• using temporary
• using filesort

Good extra values:

• using index