I try to execute the following command :
su -l user1 -c "hive -e \"ALTER TABLE schema1.table1 DROP IF EXISTS PARTITION (att1=\"$val\");\""
I get the error :
FAILED: ParseException line 1:81 cannot recognize input near 'val1' ')' '<EOF>' in constant
So the problem here is due to the 2nd level nested double quotes, between which there is the variable $val whose value is val1.
Can you help me resolve it? And the best is to give me a rule for nested quotes.
In this particular case, you can use single quotes instead of the internal (currently escaped) double quotes, since single quotes inside double quotes are not special at all.
su -l user1 -c "hive -e 'ALTER TABLE schema1.table1 DROP IF EXISTS PARTITION (att1=\"$val\");'"
In the general case, you can't always avoid death by backslash escapes. The general quoting rules are very straightforward; text between single quotes is quoted verbatim, whereas double quotes are weaker but allow you to backslash things which should not be touched by the shell.