Shell Script and SQL results

Question

I currently want to extract a value from a SQL command responde

somehting like this:

psql db -c "SELECT COUNT(test) FROM tbTest;"

the result is:

 count
------
 33176
(1 row)

I want to extract the 33176 value... is there any simple way to do this?

Answer 1

Why mucking with the unwanted stuff? Simply use some psql options...

> psql -At -c "SELECT COUNT(test) FROM tbTest;" db
115899

Answer 2

By enclosing the complete shell command in backticks, you can retrieve its result into a shell variable:

#/bin/sh

THECOUNT=`psql -A -t -c 'SELECT COUNT(*) FROM tbTest;' db`
echo "the count = $THECOUNT"

Answer 3

If it is always return in that format (expected result on line 3), you can use this:

psql db -c "SELECT COUNT(test) FROM tbTest;" | tail -n 2 | head -n 1

The explanation:

tail -n 2 will get the last 2 line and then processed by head -n 1 which mean, get first 1 line.