Sun 11 Feb 2024 05:27:33 AM UTC

Those Gawk warning messages bothered me enough to keep at the search
for a clean solution. Making use of the filefuncs(3am) library 'stat'
function provided the fix.

An example: print a list of users w/ readable ~/.wiki/ dirs:

  #!/usr/bin/gawk -E
  # wiki_users.awk -- prints users with readable wiki dirs
  @load "readdir"
  @load "filefuncs"
  BEGIN {
    FS = "/" ; H = "/home/" ; W = "/.wiki/"
    while (getline <H == 1) {
      PTH = H $2 W
      if (stat(PTH,st) == 0 && !ERRNO == 0)
        print $2
    } close(H)
  }

The 'stat(PTH,st) == 0' tests for existence, the '!ERRNO == 0' tests
for readability.  This was enough for the above case but if one wants
to filter on a particular permissions mode the 'st' array generated
contains a "pmode" index, set to a string value, i.e. "drwxr-x---".

For those unfamiliar with the readdir(3am) library, if it's loaded
then doing 'while(getline <dir == 1)' reads the contents of 'dir',
returning a string of the form "file_inode/file_name/file_type" for
each readable entry (presence of the last bit depends on filesystem
support).  Setting FS = "/" makes parsing the string easy.

Anyway, as an excuse to apply the above methods I made a RTC who-is
browser -- whodat -- which is in ~zilog/public_bin/ for anyone that
cares to use it (the lynx(1) text browser is used as the front-end).