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I want to use value returned by psql in bash. This is the script:

psql "connection parameters" -c "SELECT pg_database_size('dbname');"

The output is like this:

 pg_database_size 
------------------
          5773072
(1 row)

But I only want the 5773072 so I can use it in logging. Can anyone help?

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3 Answers

up vote 1 down vote accepted

The -t (--tuples-only) option might be used also:

psql "connection parameters" -t -c "SELECT pg_database_size('dbname');"
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In addition to what @Milen already provided, you may want -A (--no-align) remove leading white space:

psql "con params" -tAc "SELECT pg_size_pretty(pg_database_size('mydb'))"

As an aside: pg_size_pretty() may or may not be of interest.

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I got it:

psql "connection parameters" -c "SELECT pg_database_size('dbname');" | tail -3 | head -1 | tr -d ' '
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