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View the help message with PAGER [Feature #16754]

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View the help message wth pager designed by RUBY_PAGER or PAGER
environment variable, unless that value is empty.
This commit is contained in:
Nobuyoshi Nakada 2020-02-04 09:47:58 +09:00
parent 5c27681813
commit f22c4ff359
Notes: git 2020-04-12 14:58:39 +09:00
2 changed files with 37 additions and 0 deletions
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8
NEWS.md
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@ -54,6 +54,13 @@ sufficient information, see the ChangeLog file or Redmine
## Command line options
### `--help` option
When the environment variable `RUBY_PAGER` or `PAGER` is present and has
non-empty value, and the standard input and output are tty, `--help`
option shows the help message via the pager designated by the value.
[[Feature #16754]]
## Core classes updates
Outstanding ones only.
@ -192,4 +199,5 @@ Excluding feature bug fixes.
[Feature #15921]: https://bugs.ruby-lang.org/issues/15921
[Feature #16555]: https://bugs.ruby-lang.org/issues/16555
[Feature #16746]: https://bugs.ruby-lang.org/issues/16746
[Feature #16754]: https://bugs.ruby-lang.org/issues/16754
[GH-2991]: https://github.com/ruby/ruby/pull/2991

29
ruby.c
View file

@ -1606,6 +1606,35 @@ process_options(int argc, char **argv, ruby_cmdline_options_t *opt)
(argc > 0 && argv && argv[0] ? argv[0] :
origarg.argc > 0 && origarg.argv && origarg.argv[0] ? origarg.argv[0] :
ruby_engine);
#ifdef HAVE_WORKING_FORK
if (opt->dump & DUMP_BIT(help)) {
const char *pager_env = getenv("RUBY_PAGER");
if (!pager_env) pager_env = getenv("PAGER");
if (pager_env && *pager_env && isatty(0) && isatty(1)) {
VALUE pager = rb_str_new_cstr(pager_env);
int fds[2];
if (rb_pipe(fds) == 0) {
rb_pid_t pid = fork();
if (pid > 0) {
/* exec PAGER with reading from child */
dup2(fds[0], 0);
}
else if (pid == 0) {
/* send the help message to the parent PAGER */
dup2(fds[1], 1);
dup2(fds[1], 2);
}
close(fds[0]);
close(fds[1]);
if (pid > 0) {
rb_f_exec(1, &pager);
kill(SIGTERM, pid);
rb_waitpid(pid, 0, 0);
}
}
}
}
#endif
usage(progname, (opt->dump & DUMP_BIT(help)));
return Qtrue;
}