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).