ho fatto questo piccolo test:
	codice:
	#!/bin/bash -x
WANTED_BACKUPS=3
date=$(date "+%Y%m%d-%H.%M")
ssh cacao74@slack64 "
  cp /bin/bash /tmp/ksh-${date}
"
ssh cacao74@slack64 "
  TOTAL=\$(ls -1 /bin/*sh | wc -l)
  for shell in \$( ls -1 /bin/*sh | head -n \$(( \$TOTAL - $WANTED_BACKUPS )) | tail -n \$(( \$TOTAL - $WANTED_BACKUPS + 1 )) )
  do
    echo ls -l \$shell
  done
"
ssh cacao74@slack64 "
  cp /bin/ksh /tmp/ksh-${date}
"
 
output
	codice:
	cacao74@vaio:~$ ./cacao2.sh 
+ WANTED_BACKUPS=3
++ date +%Y%m%d-%H.%M
+ date=20100731-13.04
+ ssh cacao74@slack64 '
  cp /bin/bash /tmp/ksh-20100731-13.04
'
+ ssh cacao74@slack64 '
  TOTAL=$(ls -1 /bin/*sh | wc -l)
  for shell in $( ls -1 /bin/*sh | head -n $(( $TOTAL - 3 )) | tail -n $(( $TOTAL - 3 + 1 )) )
  do
    echo ls -l $shell
  done
'
ls -l /bin/ash
ls -l /bin/bash
ls -l /bin/csh
ls -l /bin/ksh
ls -l /bin/rksh
+ ssh cacao74@slack64 '
  cp /bin/ksh /tmp/ksh-20100731-13.04
'
 
se puo' servire...