A-M baby

Task/Find-common-directory-path/REXX/find-common-directory-path.rexx

@@ -0,0 +1,15 @@
+/*REXX program finds  common directory path  for a list of files.       */
+@.=                                    /*define all file lists to null. */
+@.1 = '/home/user1/tmp/coverage/test'
+@.2 = '/home/user1/tmp/covert/operator'
+@.3 = '/home/user1/tmp/coven/members'
+L=length(@.1)
+                do j=2  while @.j\=='' /*start with the second string.  */
+                _ = compare(@.j,@.1);  if _==0  then iterate    /*equal.*/
+                L = min(L,_)           /*find the minimum equal strings.*/
+                end   /*j*/
+
+common = left(@.1,lastpos('/',@.1,L))  /*find the shortest  DIR  string.*/
+if right(common,1)=='/'  then common=left(common, max(0,length(common)-1))
+say 'common directory path: ' common   /*[↑] handle trailing / delimiter*/
+                                       /*stick a fork in it, we're done.*/