3.4.2.4 Command search path

Why you should care about path?

1. Once you have read the later chapter of this book and  you try writing your own shell program, you will want to test them and eventually set aside a directory for them.
2. Your system may be set up so that certain restricted commands' executable files are kept in directories that are not listed in PATH

Add directory to PATH:put this line to .bash_profile
PATH=$PATH":/home/you/bin/"

HISTTIMEFORMAT

3.4.2. Build-in Variables
3.4.2.1. Editing mode variables

HISTTIMEFORMAT="%y/%m/%d %T "

...
78 04/11/26 17:14:05 HISTTIMEFORMAT="%y/%m/%d %T "
79 04/11/26 17:14:08 ls -l
80 04/11/26 17:14:09 history

echo "$HISTTIMEFORMAT"
%y/%m/%d %T