#! /usr/bin/env python # A rather specialized script to make sure that a symbolic link named# RCS exists pointing to a real RCS directory in a parallel tree# referenced as RCStree in an ancestor directory.# (I use this because I like my RCS files to reside on a physically# different machine). import os def main():    rcstree = 'RCStree'    rcs = 'RCS'    if os.path.islink(rcs):        print '%r is a symlink to %r' % (rcs, os.readlink(rcs))        return    if os.path.isdir(rcs):        print '%r is an ordinary directory' % (rcs,)        return    if os.path.exists(rcs):        print '%r is a file?!?!' % (rcs,)        return    #    p = os.getcwd()    up = ''    down = ''    # Invariants:    # (1) join(p, down) is the current directory    # (2) up is the same directory as p    # Ergo:    # (3) join(up, down) is the current directory    #print 'p =', repr(p)    while not os.path.isdir(os.path.join(p, rcstree)):        head, tail = os.path.split(p)        #print 'head = %r; tail = %r' % (head, tail)        if not tail:            print 'Sorry, no ancestor dir contains %r' % (rcstree,)            return        p = head        up = os.path.join(os.pardir, up)        down = os.path.join(tail, down)        #print 'p = %r; up = %r; down = %r' % (p, up, down)    there = os.path.join(up, rcstree)    there = os.path.join(there, down)    there = os.path.join(there, rcs)    if os.path.isdir(there):        print '%r already exists' % (there, )    else:        print 'making %r' % (there,)        makedirs(there)    print 'making symlink %r -> %r' % (rcs, there)    os.symlink(there, rcs) def makedirs(p):    if not os.path.isdir(p):        head, tail = os.path.split(p)        makedirs(head)        os.mkdir(p, 0777) if __name__ == "__main__":    main()