NAME

       elink - look up related NCBI Entrez records

SYNOPSIS

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

DESCRIPTION

       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.

OPTIONS

   Destination Database
       -related
              Look up neighbors in the same database.

       -target dbname
              Follow links to another database.

       -name name
              Follow  an explicit link name such as pubmed_protein_refseq, pubmed_pubmed_citedin,
              or pubmed_pubmed_refs.

   Direct Record Selection
       -db name
              Entrez database name for immediate lookups.

       -id ID(s)
              Unique identifier(s) for immediate lookups.

       -input filename (shell implementation only)
              Read identifer(s) from file instead of standard input.

   Advanced Control
       -cmd command
              Command type (returns eLinkResult XML):
              history (shell implementation only)
                     Save results in Entrez history server
              neighbor
                     Neighbors or links
              neighbor_score
                     Neighbors with computed similarity scores
              acheck All links available
              ncheck Existence of neighbors
              lcheck Existence of external links (LinkOuts)
              llinks Non-library LinkOut providers
              llinkslib (Perl) or llibs (shell)
                     All LinkOut providers
              prlinks
                     Primary LinkOut provider.

       -holding provider (Perl implementation only)
              Name of LinkOut provider.

   PubMed Citation Lookup
       -cited References to this paper.

       -cites Publication reference list.

   Batch Processing
       -batch (Perl implementation only)
              Bypass Entrez history mechanism.

   Miscellaneous Arguments
       -help  Print usage information.

ENVIRONMENT

       USE_NEW_EDIRECT
              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).

SEE ALSO

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