NAME

       feature-check — query a program for supported features

SYNOPSIS

       feature-check [-v] [-O optname] [-P prefix] program feature-name
       feature-check [-O optname] [-P prefix] program feature-name op version
       feature-check [-O optname] [-o json|tsv] [-P prefix] -l program
       feature-check -V | -h
       feature-check --features

DESCRIPTION

       The  feature-check  tool  obtains the list of supported features from a program via various methods (e.g.
       running it with the --features command-line option) and allows other programs to check for  the  presence
       and, possibly, versions of specific features.

       Options:

       --features
               List the compile-time features supported by this version of feature-check:

               feature-check
                       Always present, with the version of the feature-check tool.

               list    Present  if  the feature-check tool supports fetching the list of features supported by a
                       program.

               simple  Present if the feature-check tool supports comparing the  version  of  a  single  feature
                       against a specified version string.

               single  Present if the feature-check tool supports querying a single feature.

       -h, --help
               Display program usage output and exit.

       -O optname
               Specify the option to pass to the program to obtain its list of features (default --features).

       -o format
               Specify the output format for the full list of features with the -l option.

       -P prefix
               Specify  the  prefix  that feature-check should look for in the program's output to find the line
               that contains the list of features; default "Features: ".

       -V, --version
               Display program version output and exit.

       -v      When querying a single feature, output the version obtained for it.

EXIT STATUS

       When querying a single feature, feature-check will exit with code 0 if the program supports that feature,
       and with a non-zero code when either the program could not be executed, or its list of features could not
       be parsed, or the feature was not present.

       When examining the version of a single feature, feature-check will exit with code  0  if  the  comparison
       result  is  true,  and with a non-zero code when either the program could not be executed, or its list of
       features could not be parsed, or the comparison failed.

       When listing the features supported by a program, feature-check will exit with code 0 when  the  list  of
       features  was obtained and output, and with a non-zero code when either the program could not be executed
       or its list of features could not be parsed.

EXAMPLES

       The following examples are shown as given to the shell:

             feature-check curl AsynchDNS

       Exit with code 0 if the curl(1) tool is present and it supports asynchronous DNS lookups.

             feature-check -l confget

       List the features supported by the confget(1) tool.

             feature-check timelimit 'timelimit ge 1.9'

       Exit with code 0 if the timelimit(1) tool advertises its timelimit feature at version 1.9 or later.

             feature-check timelimit timelimit ge 1.9

       The same check; note that the feature-check tool will treat all the arguments after the program name as a
       single expression, i.e. it will concatenate them into a  single  string  separated  by  spaces  and  then
       interpret the string.

STANDARDS

       No standards documentation was harmed in the process of creating feature-check.

BUGS

       Please report any bugs in feature-check to the author.

AUTHOR

       The feature-check utility was written by Peter Pentchev <roam@ringlet.net> in 2018.

Debian                                           April 21, 2018                                 FEATURE-CHECK(1)