Interactive help
Demonstrate any interactive (or command line) help offered by the language implementation.
This can be for exploring features or syntax, or perhaps a simple message on where to find more information.
AWK
<lang AWK>
- syntax: GAWK --help
</lang>
- Output:
Usage: gawk [POSIX or GNU style options] -f progfile [--] file ... Usage: gawk [POSIX or GNU style options] [--] 'program' file ... POSIX options: GNU long options: (standard) -f progfile --file=progfile -F fs --field-separator=fs -v var=val --assign=var=val Short options: GNU long options: (extensions) -b --characters-as-bytes -c --traditional -C --copyright -d[file] --dump-variables[=file] -D[file] --debug[=file] -e 'program-text' --source='program-text' -E file --exec=file -g --gen-pot -h --help -i includefile --include=includefile -l library --load=library -L [fatal] --lint[=fatal] -n --non-decimal-data -M --bignum -N --use-lc-numeric -o[file] --pretty-print[=file] -O --optimize -p[file] --profile[=file] -P --posix -r --re-interval -S --sandbox -t --lint-old -V --version To report bugs, see node `Bugs' in `gawk.info', which is section `Reporting Problems and Bugs' in the printed version. gawk is a pattern scanning and processing language. By default it reads standard input and writes standard output. Examples: gawk '{ sum += $1 }; END { print sum }' file gawk -F: '{ print $1 }' /etc/passwd
Go
The 'go doc' command line tool shows documentation for either a package or a symbol within a package.
For example, here we list the exported functions and types in the 'strings' package in the standard library:
$ go doc strings package strings // import "strings" Package strings implements simple functions to manipulate UTF-8 encoded strings. For information about UTF-8 strings in Go, see https://blog.golang.org/strings. func Compare(a, b string) int func Contains(s, substr string) bool func ContainsAny(s, chars string) bool func ContainsRune(s string, r rune) bool func Count(s, substr string) int func EqualFold(s, t string) bool func Fields(s string) []string func FieldsFunc(s string, f func(rune) bool) []string func HasPrefix(s, prefix string) bool func HasSuffix(s, suffix string) bool func Index(s, substr string) int func IndexAny(s, chars string) int func IndexByte(s string, c byte) int func IndexFunc(s string, f func(rune) bool) int func IndexRune(s string, r rune) int func Join(a []string, sep string) string func LastIndex(s, substr string) int func LastIndexAny(s, chars string) int func LastIndexByte(s string, c byte) int func LastIndexFunc(s string, f func(rune) bool) int func Map(mapping func(rune) rune, s string) string func Repeat(s string, count int) string func Replace(s, old, new string, n int) string func Split(s, sep string) []string func SplitAfter(s, sep string) []string func SplitAfterN(s, sep string, n int) []string func SplitN(s, sep string, n int) []string func Title(s string) string func ToLower(s string) string func ToLowerSpecial(c unicode.SpecialCase, s string) string func ToTitle(s string) string func ToTitleSpecial(c unicode.SpecialCase, s string) string func ToUpper(s string) string func ToUpperSpecial(c unicode.SpecialCase, s string) string func Trim(s string, cutset string) string func TrimFunc(s string, f func(rune) bool) string func TrimLeft(s string, cutset string) string func TrimLeftFunc(s string, f func(rune) bool) string func TrimPrefix(s, prefix string) string func TrimRight(s string, cutset string) string func TrimRightFunc(s string, f func(rune) bool) string func TrimSpace(s string) string func TrimSuffix(s, suffix string) string type Builder struct{ ... } type Reader struct{ ... } func NewReader(s string) *Reader type Replacer struct{ ... } func NewReplacer(oldnew ...string) *Replacer BUG: The rule Title uses for word boundaries does not handle Unicode punctuation properly.
We can now 'dig down' to obtain the documentation for the TrimSpace function wthin the strings package:
$ go doc strings.TrimSpace func TrimSpace(s string) string TrimSpace returns a slice of the string s, with all leading and trailing white space removed, as defined by Unicode.
and to list the methods of the strings.Replacer struct:
$ go doc strings.Replacer type Replacer struct { // Has unexported fields. } Replacer replaces a list of strings with replacements. It is safe for concurrent use by multiple goroutines. func NewReplacer(oldnew ...string) *Replacer func (r *Replacer) Replace(s string) string func (r *Replacer) WriteString(w io.Writer, s string) (n int, err error)
Finally, we obtain the documentation for the strings.Replacer.WriteString method:
$ go doc strings.Replacer.WriteString func (r *Replacer) WriteString(w io.Writer, s string) (n int, err error) WriteString writes s to w with all replacements performed.
The 'go doc' tool also has some flags including a flag to list both exported and unexported symbols (-u) and to respect case when matching symbols (-c); normally lower- case letters match either case.
Jsish
prompt$ jsish Jsish interactive: see 'help [cmd]' # help Jsish interactive executes commands, uses tab for completions, and has help for the following builtin commands: Array Boolean CData CEnum CStruct CType Channel Debugger Event File Function Info Interp JSON Math Number Object RegExp Signal Socket Sqlite String System Util Vfs WebSocket Zvfs assert clearInterval console decodeURI encodeURI exec exit format isFinite isMain isNaN load log noOp parseFloat parseInt parseOpts printf provide puts quote require runModule setInterval setTimeout sleep source strftime strptime unload update Help can also take options. For example to display in a web browser try: help -web true WebSocket Module help can also be displayed (non-web), as in 'help Jsi_Websrv`. Builtin modules include: Jsi_Archive Jsi_CData Jsi_Csspp Jsi_Debug Jsi_DebugUI Jsi_GenDeep Jsi_Help Jsi_Htmlpp Jsi_Jspp Jsi_Markdeep Jsi_Module Jsi_Safe Jsi_SqliteUI Jsi_UnitTest Jsi_Vfs Jsi_Websrv Jsi_Wget # help File File.method(...) Commands for accessing the filesystem Methods: atime chdir chmod copy dirname executable exists extension glob isdir isfile isrelative join link lstat mkdir mknod mtime owned pwd read readable readlink realpath remove rename rootname size stat tail tempfile truncate type writable write [File.glob options] Option Type Description [Flags] ---------------------------------------------------------------------------- dir STRING The start directory: this path will not be prepended to results. maxDepth INT Maximum directory depth to recurse into. maxDiscard INT Maximum number of items to discard before giving up. dirFilter FUNC Filter function for directories, returning false to discard. @function(dir:string) filter FUNC Filter function to call with each file, returning false to discard. @function(file:string) limit INT The maximum number of results to return/count. noTypes STRKEY Filter files to exclude these "types". prefix STRKEY String prefix to add to each file in list. recurse BOOL Recurse into sub-directories. retCount BOOL Return only the count of matches. tails BOOL Returned only tail of path. types STRKEY Filter files to include type: one or more of chars 'fdlpsbc' for file, directory, link, etc.
Perl
- When invoked as
perl -h
at the command line:
Usage: perl [switches] [--] [programfile] [arguments] -0[octal] specify record separator (\0, if no argument) -a autosplit mode with -n or -p (splits $_ into @F) -C[number/list] enables the listed Unicode features -c check syntax only (runs BEGIN and CHECK blocks) -d[:debugger] run program under debugger -D[number/list] set debugging flags (argument is a bit mask or alphabets) -e program one line of program (several -e's allowed, omit programfile) -E program like -e, but enables all optional features -f don't do $sitelib/sitecustomize.pl at startup -F/pattern/ split() pattern for -a switch (//'s are optional) -i[extension] edit <> files in place (makes backup if extension supplied) -Idirectory specify @INC/#include directory (several -I's allowed) -l[octal] enable line ending processing, specifies line terminator -[mM][-]module execute "use/no module..." before executing program -n assume "while (<>) { ... }" loop around program -p assume loop like -n but print line also, like sed -s enable rudimentary parsing for switches after programfile -S look for programfile using PATH environment variable -t enable tainting warnings -T enable tainting checks -u dump core after parsing program -U allow unsafe operations -v print version, patchlevel and license -V[:variable] print configuration summary (or a single Config.pm variable) -w enable many useful warnings -W enable all warnings -x[directory] ignore text before #!perl line (optionally cd to directory) -X disable all warnings Run 'perldoc perl' for more help with Perl.
- Running
perldoc perl
, output includes (but is not limited to):
GETTING HELP The perldoc program gives you access to all the documentation that comes with Perl. You can get more documentation, tutorials and community support online at <http://www.perl.org/>. If you're new to Perl, you should start by running "perldoc perlintro", which is a general intro for beginners and provides some background to help you navigate the rest of Perl's extensive documentation. Run "perldoc perldoc" to learn more things you can do with perldoc. For ease of access, the Perl manual has been split up into several sections. Overview perl Perl overview (this section) perlintro Perl introduction for beginners perlrun Perl execution and options perltoc Perl documentation table of contents Tutorials perlreftut Perl references short introduction perldsc Perl data structures intro perllol Perl data structures: arrays of arrays perlrequick Perl regular expressions quick start perlretut Perl regular expressions tutorial perlootut Perl OO tutorial for beginners perlperf Perl Performance and Optimization Techniques perlstyle Perl style guide perlcheat Perl cheat sheet perltrap Perl traps for the unwary perldebtut Perl debugging tutorial perlfaq Perl frequently asked questions perlfaq1 General Questions About Perl perlfaq2 Obtaining and Learning about Perl perlfaq3 Programming Tools perlfaq4 Data Manipulation perlfaq5 Files and Formats perlfaq6 Regexes perlfaq7 Perl Language Issues perlfaq8 System Interaction perlfaq9 Networking Reference Manual perlsyn Perl syntax perldata Perl data structures perlop Perl operators and precedence perlsub Perl subroutines perlfunc Perl built-in functions perlpod Perl plain old documentation perldiag Perl diagnostic messages perldeprecation Perl deprecations perllexwarn Perl warnings and their control perldebug Perl debugging perlvar Perl predefined variables perlre Perl regular expressions, the rest of the story perlref Perl references, the rest of the story perlobj Perl objects perltie Perl objects hidden behind simple variables perlipc Perl interprocess communication perlfork Perl fork() information perlnumber Perl number semantics perlthrtut Perl threads tutorial perlport Perl portability guide perllocale Perl locale support perlunicode Perl Unicode support perlunifaq Perl Unicode FAQ perlunitut Perl Unicode tutorial perlsec Perl security perlmod Perl modules: how they work perlmodlib Perl modules: how to write and use perlmodinstall Perl modules: how to install from CPAN perlutil utilities packaged with the Perl distribution perlglossary Perl Glossary perlbook Perl book information perlcommunity Perl community information perldoc Look up Perl documentation in Pod format perldelta Perl changes since previous version
Perl 6
Perl 6 help is generally in a specialized text format known as POD (Plain Old Documentation). It is sometimes referred to as POD6 to distinguish it from Perl 5 POD which is slightly different and not completely compatible. Perl 6 has a local command line help app: p6doc. It also has online browsable HTML documentation at docs.perl6.org. If you want to download the HTML docs for a local copy, or just prefer to browse the documentation as a single page docs.perl6.org/perl6.html may be more to your preference. If you prefer a different format, there are utilities available to convert the POD docs to several different formats; Markdown, PDF, Latex, plain text, etc.
Individual Perl 6 scripts are to some extent self-documenting. If the script has a MAIN sub, and it is called with improper parameters, it will display an automatically generated help message showing the various possible parameters, which are required, which are optional, and what type each takes:
<lang perl6>sub MAIN(
Str $run, #= Task or file name Str :$lang = 'perl6', #= Language, default perl6 Int :$skip = 0, #= Skip # to jump partially into a list Bool :f(:$force), #= Override any skip parameter
) {
# do whatever
}</lang>
- When saved locally as main.p6 and invoked with no (or wrong) passed parameters:
Usage: main.p6 [--lang=<Str>] [--skip=<Int>] [-f|--force] <run> <run> Task or file name --lang=<Str> Language, default perl6 --skip=<Int> Skip # to jump partially into a list -f|--force Override any skip parameter
Phix
See docs\phix\phix.chm for the complete manual, or online.
When p -?, p -h, p -help, or p --help is entered:
interpret: <filename> compile: -c <filename> also: -d creates a list.asm file, -nodiag creates a smaller list.asm file, -norun may be useful in batch jobs, -test, tnn, b, bt, etc, and of course -c p, which rebuilds the compiler. for more details\options see pth.exw. Wildcards are allowed, as long as they select a single file, with ".exw" assumed, eg "demo\tak*" runs demo\takeuchi.exw. Press F7 to list prompt history, up/down to select. Phix hybrid interpreter/compiler. Version 0.8.0 (32 bit Windows) Copyright Pete Lomax 2006..2016 Enter ? for options or filename to execute:
(Pressing ? at that last prompt would re-display the text just shown.)
REXX
Some REXXes offer interactive help (via HELP or some other command).
Other REXXes have an HTML document or a PDF for showing command syntax and other general information on use of the language.
Each REXX has it's own documentation, and viewing it would depend on the host environment.