Fruits of my labor

["Scott C. Gray" <gray@nas.nasa.gov>]

For those of you that really care, here is my little cd replacement.  It is 
rather large because it replaces all of the functionality of the builtin cd, 
yet still manages to call only one external program during creation.

# cd [ -[N] | dir ]
#
# This replaces the builtin version of cd, absorbing all of its features
# and adding the ability to jump back to the Nth previous directory. The
# number of previous directories that cd remembers may be adjusted by
# incrementing cd-stack-depth.  The size of the stack is actually
# cd-stack-depth + 1 (if cd-stack-depth is not set, then the stack becomes
# unabounded).

cd-stack-depth = 3
let ( cd-stack = .; cwd = `pwd ) {
   fn cd dir { 
      if {~ $#dir 0} {
         if {! ~ $#home 1} {
            throw error cd <={
               if {~ $#home 0} {
                  result 'cd: $home not set'
               } {
                  result 'cd: $home contains more than one word'
               }
            }
         }
         dir = $home
      } {~ $#dir 1} {
         if { ~ $dir -* } {
            let (index = <={%split - $dir}) {
               if {~ $#index 0} {
                  index = 1
               } { ! ~ $index [0-9]* } {
                  throw error cd 'cd: invalid argument'
               }
               dir = $cd-stack($index)
               echo $dir >[1=2]
            }
            if { ~ $#dir 0 } {
               throw error cd 'cd: stack not that deep'
            }
         } {! %is-absolute $dir} {
            let (old = $dir) {
               dir = <={%cdpathsearch $dir}
               if {! ~ $dir $old} {
                  echo $dir >[1=2]
               }
            }
         }
      } {
         throw error cd 'usage: cd [-[N]|[directory]]'
      }

      if {$&cd $dir} {
         cd-stack = ($cwd $cd-stack( 1 ... $cd-stack-depth ))
         cwd = $dir
      }
   }
}

-scott
--
   _/    _/   _/_/_/  _/_/_/_/   _/_/_/  Scott C. Gray (gray@nas.nasa.gov)
  _/_/  _/  _/    _/ _/_/      _/    _/  NASA Ames Research M/S 258-6
 _/  _/_/  _/_/_/_/     _/_/  _/_/_/_/   For PGP public key, send me mail
_/    _/  _/    _/ _/_/_/_/  _/    _/    with subject line of "PGP request".