NAME

       esearch - search an NCBI Entrez database

SYNOPSIS

       esearch   (edirect -search)  [-help]  -db name  -q[uery] str  [-sort field]  [-days N]  [-datetype field]
       [-mindate date] [-maxdate date] [-field field] [-pairs field] [-spell]

DESCRIPTION

       esearch searches an NCBI Entrez database for a given query.

       It has two  implementations:  a  shell  implementation  on  top  of  nquire(1)  and  a  traditional  Perl
       implementation  that  amounts  to  running  edirect  -search, 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.   In  addition,  the  shell  implementation
       accepts  the  full  range  of  efilter(1)  options,  whereas  the  Perl implementation accepts only those
       specifically mentioned below.

OPTIONS

   Query Specification
       -db name
              Entrez database name.

       -q str (Perl implementation only)
       -query str
              Query string.

   Document Order
       -sort field
              Sort results by the given field.

   Date Constraint
       -days N
              Return only results from the past N days.

       -datetype field
              Which date field (in abbreviated form) to consider.

       -mindate date
              Start of date range.

       -maxdate date
              End of date range.

   Limit by Field
       -field field (Perl implementation only)
              Query words individually in field.

       -pairs field (Perl implementation only)
              Query overlapping word pairs.

   Spell Check
       -spell Correct misspellings in query.

   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),  efetch(1),  efilter(1),  eproxy(1), espell(1), exclude-uid-lists(1), intersect-uid-lists(1),
       nquire(1).

NCBI                                               2021-03-07                                         ESEARCH(1)