I am using the following one-liner with NCBI entrez to query their databases from the terminal (see Entrez Direct: E-utilities on the Unix Command Line:

esearch -db assembly -query ${species name} |
    xtract -pattern ENTREZ_DIRECT -element Count

This works a charm but occasionally it sends an xml error that messes up the output.

Here is an example of the error:

FAILURE ( Fri Jan 27 01:12:44 PM CST 2023 )
nquire -url https://eutils.ncbi.nlm.nih.gov/entrez/eutils/ esearch.fcgi -retmax 0 -usehistory y -db assembly -term "Crepis commutata" -tool edirect -edirect 18.7 -edirect_os Linux -email {}
  <PhraseNotFound>Crepis commutata[All Fields]</PhraseNotFound>

Entrez, unfortunately, does not have a man page or --help entry on my installation for some reason and I am not quite sure where I should change the one-liner to change this behavior.

Does anyone have any clues?


1 Answer 1


This is because there are not assemblies for Crepis commutate within NCBI's assembly database.

The cross check is here:


The output is a bit clearer than Entrez

The following terms were not found in Assembly: commutata, Crepis commutata[All Fields]. No items found.

All you need do to correct it is issue a next statement in the a loop of species above the code you've presented.

if [[ "$species" == 'Crepis commutata' ]]; then
esearch -db assembly -query "$species" | xtract -pattern ENTREZ_DIRECT -element Count

To answer the comments if this is done via a Python subprocess, you could simply issue the following code (which has not been checked)

import subprocess

for species in List:
        subprocess.run(["esearch", "-db" "assembly", "-query", f"${species}", "|", "xtract", "-pattern", "ENTREZ_DIRECT", "-", "element"], shell=True")
    except ValueError as ve:
        print(f'Species {species}, is not present.')
  • $\begingroup$ Right but is there a way to set entrez tools to pipe the error? Being able to do that would help me clean up the output produced from an automated session a bit easier. Crepis commutate no existing on NCBI is not the issue, rather not being able to cleanly pipe the outcome is the issue. $\endgroup$
    – Sudoh
    Jan 27 at 19:38
  • 1
    $\begingroup$ 2>&1 Merge stderr into stdout ; stackoverflow.com/questions/818255/what-does-21-mean $\endgroup$
    – pippo1980
    Jan 27 at 23:35

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