help
Display command usage information
TLDR
Display the full list of builtin commands
Print instructions on how to use the while loop construct
Print instructions on how to use the for loop construct
Print instructions on how to use [[ ]] for conditional commands
Print instruction on how to use (( )) to evaluate arithmetic expressions
Print instructions on how to use the cd command
SYNOPSIS
help [-dEhmqs] [-o opt] [pattern ...]
PARAMETERS
-d
print a short description, or usage synopsis for some builtins
-E
classify functions into basic/reserved/special
-h
display help for help itself and exit
-m
display help in pseudo-manpage format
-o opt
set output format (e.g., json, xml, vim)
-q
quiet mode; suppress output if no match found
-s
print only a short usage synopsis, like --help
DESCRIPTION
The help command is a Bash shell built-in utility designed to provide concise documentation and usage information specifically for other Bash built-in commands. Bash builtins, such as cd, echo, and read, lack traditional man pages, making help the primary source for their syntax, options, and behavior.
Invoked without arguments, help lists all available built-ins in a formatted table. Specifying a command name, like help cd, outputs detailed help for that builtin. It supports shell glob patterns (e.g., help cd *) to match and display help for multiple commands.
Various options control output format: short synopses for quick reference, manpage-style for readability, or even structured formats like JSON. This makes help invaluable for interactive shell use, scripting, and learning Bash internals. It extracts information directly from Bash's internal documentation strings, ensuring accuracy tied to the current shell version.
Primarily useful in Bash environments, help enhances productivity by keeping documentation accessible without external tools, though it does not cover POSIX builtins or external utilities.
CAVEATS
Only works for Bash built-ins, not external commands or functions unless marked as such. Output depends on Bash version; unavailable in non-Bash shells like dash.
EXAMPLES
help # List all builtins
help cd # Help for cd
help -m read # Manpage-style for read
help -s *e* # Short help for matching builtins
NO MATCH BEHAVIOR
Exits with status 1 if no builtins match the pattern; use -q to suppress errors.
HISTORY
Introduced in Bash 2.0 (1996) to address lack of documentation for builtins. Enhanced in later versions: Bash 4.0 added -m; Bash 4.4 added -o formats; Bash 5.0 expanded options like -E and -q.
