The importance of adding < /dev/null with while loops

[nickp60]

I've been tricked by this several times, and thought it would be a good addition to the Cookbook. When using while loops without adding the </dev/null after the input the input, only the first line will be processed. Here is the (slightly modified) example from the docs:

  while read org
  do
    esearch -db taxonomy -query "$org [LNGE] AND family [RANK]" < /dev/null |
    efetch -format docsum |
    xtract -pattern DocumentSummary -lbl "$org" \
      -element ScientificName Division
  done <  organisms


(The "< /dev/null" input redirection construct prevents esearch from "draining" the remaining lines from stdin.)

I can make a pull request is this is repo is still being supported.