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ELINK(1) NCBI Entrez Direct User's Manual ELINK(1)


elink - look up related NCBI Entrez records


elink (edirect -link) [-help] [-related] [-target dbname] [-name name] [-db name] [-id ID(s)] [-input filename] [-cmd command] [-holding provider] [-cited] [-cites] [-batch]


elink follows links between Entrez databases, either extending an existing edirect(1) pipeline or honoring explicit -db and -id (or -input) options.

It has two implementations: a shell implementation on top of nquire(1) and a historical Perl implementation that amounts to running edirect -link, enabled by setting the environment variable USE_NEW_EDIRECT to a false value as described in the ENVIRONMENT section. Some options are implementation-specific, as detailed below.


Destination Database

Look up neighbors in the same database.
Follow links to another database.
Follow an explicit link name such as pubmed_protein_refseq, pubmed_pubmed_citedin, or pubmed_pubmed_refs.

Direct Record Selection

Entrez database name for immediate lookups.
Unique identifier(s) for immediate lookups.
Read identifer(s) from file instead of standard input.

Advanced Control

Command type (returns eLinkResult XML):
Save results in Entrez history server
Neighbors or links
Neighbors with computed similarity scores
All links available
Existence of neighbors
Existence of external links (LinkOuts)
Non-library LinkOut providers
All LinkOut providers
Primary LinkOut provider.
Name of LinkOut provider.

PubMed Citation Lookup

References to this paper.
Publication reference list.

Batch Processing

Bypass Entrez history mechanism.

Miscellaneous Arguments

Print usage information.


Whether to use the current shell implementation or revert to the historical Perl implementation. Canonical true values are 1, on (case-insensitive), true (case-insensitive), and yes (case-insensitive); canonical false values are 0, off (case-insensitive), false (case-insensitive), and no (case-insensitive).


edirect(1), einfo(1), epost(1), nquire(1), protein-neighbors(1).

2021-03-07 NCBI