Cheat sheet on how to write shell scripts

at the to, put:
#!/bin/bash


generate timestamp: `date +"%Y%m%d_%H%M"`

to append each command output to a log file AND send to console :
command | tee -a mylog.log

checking result of last command (it's the $? ):

if [ $? -ne 0 ]

then

   echo OK

else

   echo KO

fi

to assign positional parameters:
set -- BLA
the result is that $1=BLA