title: Unable to find out what the data directory is for PostgreSQL in Mac OS X
body: <p>I hava PostgreSQL 9.3 installed by homebrew in Mac OS X 10.9.3. When I first installed it, it worked well. After reboot it happened to be not launched and I don’t know how to launch by <code>pg_ctl</code> it because I can't find out what its data directory is:</p>
  
  <pre><code>$ pg_ctl start
  pg_ctl: no database directory specified and environment variable PGDATA unset
  Try "pg_ctl --help" for more information.
  
  $ pwd
  /usr/local/var/postgres
  
  $ ls -al
  total 96
  drwx------  21 alex  admin    714 Jun  2 21:23 .
  drwx------   3 alex  admin    102 Jun  1 15:08 ..
  -rw-------   1 alex  admin      4 Jun  1 15:08 PG_VERSION
  drwx------   6 alex  admin    204 Jun  2 11:40 base
  drwx------  42 alex  admin   1428 Jun  2 14:18 global
  drwx------   3 alex  admin    102 Jun  1 15:08 pg_clog
  -rw-------   1 alex  admin   4465 Jun  2 10:58 pg_hba.conf
  -rw-------   1 alex  admin   1636 Jun  1 15:08 pg_ident.conf
  drwx------   4 alex  admin    136 Jun  1 15:08 pg_multixact
  drwx------   3 alex  admin    102 Jun  1 18:24 pg_notify
  drwx------   2 alex  admin     68 Jun  1 15:08 pg_serial
  drwx------   2 alex  admin     68 Jun  1 15:08 pg_snapshots
  drwx------   7 alex  admin    238 Jun  2 21:23 pg_stat
  drwx------   2 alex  admin     68 Jun  2 21:23 pg_stat_tmp
  drwx------   3 alex  admin    102 Jun  1 15:08 pg_subtrans
  drwx------   2 alex  admin     68 Jun  1 15:08 pg_tblspc
  drwx------   2 alex  admin     68 Jun  1 15:08 pg_twophase
  drwx------   4 alex  admin    136 Jun  1 15:08 pg_xlog
  -rw-------   1 alex  admin  20571 Jun  1 15:08 postgresql.conf
  -rw-------   1 alex  admin     79 Jun  1 18:24 postmaster.opts
  -rw-------   1 alex  admin   1482 Jun  2 21:23 server.log
  </code></pre>
  
  <p>In <code>/Library</code> there is nothing titled <code>PostgreSQL</code> or something. </p>
  
  <p>How do I find it out?</p>
  
  <p><strong>UPDATE</strong>:</p>
  
  <pre><code>$ sudo chown -R _postgres /usr/local/var/postgres
  $ ls -ld /usr/local/var/postgres
  drwx------  21 _postgres  admin  714 Jun  2 21:23 /usr/local/var/postgres
  
  #################
  
  $ sudo -u _postgres pg_ctl -D /usr/local/var/postgres -w start
  could not identify current directory: Permission denied
  pg_ctl: could not open PID file "/usr/local/var/postgres/postmaster.pid": Permission denied
  
  $ ls -al /usr/local/var/postgres/postmaster.pid
  ls: /usr/local/var/postgres/postmaster.pid: Permission denied
  
  $ sudo ls -al /usr/local/var/postgres/postmaster.pid
  ls: /usr/local/var/postgres/postmaster.pid: No such file or directory
  </code></pre>