Given a folder with files using a design name as part of the file, I want to run `svn rename` on matches to the design name. The directory listing showing the files (more than shown here) has this format:

```
    reg_ptst_lib_ptst_rtl_12.ngc
    reg_ptst_lib_ptst_rtl_13.ngc
    reg_ptst_lib_ptst_rtl_14.ngc
    reg_ptst_lib_ptst_rtl_15.ngc

```

The design name string is ptst.
I want to have the script iterate over each file, executing something like this command:

```
$svn rename reg_ptst_lib_ptst_rtl_12.ngc reg_scst3_lib_scst3_rtl_12.ngc  

```

to change the design name from `ptst` to `scst3` in subversion.