The command unset
a shell builtin of bash
- so it's in the man page of bash
.
Also, you get a shorter description with the command help
- often help unset
may explain what you need.
To find it in the man page, find it in the section "SHELL BUILTIN COMMANDS" manually,
or search for unset \[
.
Or, if you want, all in one command, for this special case:
man bash | less -p 'unset \['
The section for unset from man bash
"SHELL BUILTIN COMMANDS":
unset [-fv] [-n] [name ...]
For each name, remove the corresponding variable or func‐
tion. If the -v option is given, each name refers to a
shell variable, and that variable is removed. Read-only
variables may not be unset. If -f is specified, each name
refers to a shell function, and the function definition is
removed. If the -n option is supplied, and name is a vari‐
able with the nameref attribute, name will be unset rather
than the variable it references. -n has no effect if the
-f option is supplied. If no options are supplied, each
name refers to a variable; if there is no variable by that
name, any function with that name is unset. Each unset
variable or function is removed from the environment passed
to subsequent commands. If any of COMP_WORDBREAKS, RANDOM,
SECONDS, LINENO, HISTCMD, FUNCNAME, GROUPS, or DIRSTACK are
unset, they lose their special properties, even if they are
subsequently reset. The exit status is true unless a name
is readonly.
(From man page of bash 4.3 on Ubuntu 14.4)