rename files

   for i in 2mD* ; do 
         mv $i test-"$i"; 
   done;


   for i in P* ; do 
      new=`echo $i | sed s/"Picture "/course-Picture_/g`; 
      mv "$i" $new; 
   done; 

File re-namer (http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO-12.html#ss12.3)

File re-namer (http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO-12.html#ss12.4)

shell: expresiones aritmeticas

Hay dos posibilidades, utilizar el operador aritmetico $(()):

i=1
i=$(($i+1))
echo $i

o bien el comando shell 'expr':

i=1
i=`expr $i + 1`
echo $i

AH

noclobber / shell options / overwrite files

set -o noclobber
set -C  (es equivalente al anterior)

overwrite: NOT ALLOWED

% set -C
% ll > 1
bash: 1: cannot overwrite existing file
% set | grep SHELLOPTS
SHELLOPTS=braceexpand:emacs:hashall:histexpand:history:interactive-comments:moni

overwrite: ALLOWED

% set +C
% ll > 1
%
% set | grep SHELLOPTS
SHELLOPTS=braceexpand:emacs:hashall:histexpand:history:interactive-comments:moni