pushd [ -sLP ] [ arg ]
pushd [ -sLP ] old new
pushd [ -sLP ] {+|-}n
       Change the current directory, and push the old current directory
       onto the directory stack.  In the first form, change the current
       directory to arg.  If arg is not specified, change to the second
       directory  on the stack (that is, exchange the top two entries),
       or change to $HOME if the PUSHD_TO_HOME  option  is  set  or  if
       there  is only one entry on the stack.  Otherwise, arg is inter-
       preted as it would be by cd.  The meaning of old and new in  the
       second form is also the same as for cd.

       The third form of pushd changes directory by rotating the direc-
       tory list.  An argument of the  form  `+n'  identifies  a  stack
       entry  by  counting  from the left of the list shown by the dirs
       command, starting with zero.   An  argument  of  the  form  `-n'
       counts  from  the  right.  If the PUSHD_MINUS option is set, the
       meanings of `+' and `-' in this context are swapped.

       If the option PUSHD_SILENT is not set, the directory stack  will
       be printed after a pushd is performed.

       The  options  -s, -L and -P have the same meanings as for the cd
       builtin.
