Tips and Tricks

A collection of random tid-bits I come across during my everyday life which I cannot keep organized anywhere else.

Vim tab completion is slow

This happens if the autocompletion has to search through a large file you once opened but have since closed (SuperTab does that, for example).

Close such buffer by first viewing their number via :ls and then :bwipeout <number-of-buffer>.

Convert epoch to TIMESTAMP for PostgreSQL

SELECT TIMESTAMP 'epoch' + 1373252173850 * INTERVAL '1 millisecond'

hash index on PostgresSQL take too long to create

I think if there are a lot of repeated values in a column, the hash index takes too long to create because of collisions. It is better to use the default btree indexes in those cases.

Different prompt when on a remote machine

I often have to recall instead of recognize whether I am on a remote machine or a local machine because I have the same .bashrc on both machines.

This snippet in my .bashrc includes (in bright red color) a string in my bash prompt warning me if I am on a remote machine:

SESSION_TYPE=local
if [ -n "$SSH_CLIENT" ] || [ -n "$SSH_TTY" ]; then
  SESSION_TYPE=remote/ssh
else
  case $(ps -o comm= -p $PPID) in
    sshd|*/sshd) SESSION_TYPE=remote/ssh;;
  esac
fi

if [ "$SESSION_TYPE" != "local" ]; then
    PS1="${PS1::-2}[\033[01;31m\](ssh session)\[\033[00m\]$ ";
fi

Naming screens

Give names to screen sessions by pressing Ctrl-a followed by :sessionname <name>. Then the screen can be reattached thusly: screen -r <name>.