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.TH YOM-HOOKS 3 "2026-07-18" "v2.2.6" "YOM User Manual"
.SH NAME
yom-hooks \- lightweight hook API for the YOM shell
.SH SYNOPSIS
.B hook
.I HOOKED
.I PATH
.SH DESCRIPTION
The YOM-hook API allows you to replace
.I YOM
builtins with a specified binary. The following hooks are accepted:
.I builtins, cd, core, echo, eval, exit, pwd, read.
.SH HOW TO USE
To use hooks, write the command in a file and execute it with YOM:
.RS
.EX
hook <HOOKED> <PATH/TO/HOOK>
.EE
.RE
.PP
To target all builtins simultaneously, use the shortcut:
.RS
.EX
hook builtins <PATH/TO/HOOK>
.EE
.RE
The
.I <PATH/TO/HOOK>
parameter specifies the location of the hook binary. This path can start from the home directory (indicated by a tilde \(a~) or the root directory (indicated by a slash /).
.PP
To disable a hook and revert to the default behavior, run:
.RS
.EX
hook <HOOKED> default
.EE
.RE
.SS BUILTINS
.B yom
provides hooks for all of its builtins:
.I builtins, cd, echo, exit, pwd, read.
The
.I builtins
keyword is a shortcut that applies the hook to all available builtins.
.SS CORE & EVAL
The
.I core
hook is used to add an interactivity layer. The syntax is identical to other hooks:
.RS
.EX
hook core <PATH/TO/HOOK>
.EE
.RE
The
.B eval
hook uses the same syntax:
.RS
.EX
hook eval <PATH/TO/HOOK>
.EE
.RE
The purpose of
.B eval
is to add new commands by evaluating the input string and either running it or exiting.
.SH API
.SS API NOTES
All
.B yom
hooks pass their hook name as
.I arg1
(using the lowercase names listed above).
.SS CD
The
.B cd
hook passes the target directory as
.I arg2
and pipes stdout. Simply write the full path of the destination directory to
.I stdout.
Full access to
.I stdin
and
.I stderr
is granted.
.SS CORE
The
.B core
hook configures
.B yom
to act as a login shell. It requires you to bind to the following socket:
.RS
.EX
/tmp/yom_core.sock
.EE
.RE
Every time a user inputs a command,
.RS
.EX
eval <COMMAND>
.EE
.RE
is sent down the socket, terminated by a newline.
.B yom
will then return one of two responses:
.IP \(bu 2
.B C
followed by a newline if the directory has not changed.
.IP \(bu 2
.BI : </path/to/new/directory/>
followed by a newline to indicate a directory change.
.PP
Once the
.B core
process dies,
.B yom
cleans up the environment. The
.B core
hook only needs to exit when explicitly instructed by the user. Full access to
.I stdin,
.I stdout,
and
.I stderr
is granted.
.SS ECHO
The
.B echo
hook passes the string to be printed as
.I arg1.
It retains full access to
.I stdin,
.I stdout,
and
.I stderr.
.SS EVAL
The
.B eval
hook runs at the beginning of every processing cycle. The hook name is passed as
.I arg1,
and the string to evaluate is passed as
.I arg2.
If the string matches an executable command, exit with code
.B 0.
Any other exit code indicates no match. Full access to standard I/O
.RI ( stdin,
.I stdout,
and
.IR stderr )
is granted.
.SS EXIT
The
.B exit
hook receives the target exit code as
.I arg2.
The exit code returned by your hook will become the final shell exit code. Full access to
.I stdin,
.I stdout,
and
.I stderr
is granted.
.SS PWD
The
.B pwd
hook has full access to
.I stdin,
.I stdout,
and
.I stderr.
.SS READ
The
.B read
hook replaces the native
.B read
builtin. It should print the user-provided value directly to
.I stdout.
Full access to
.I stdin
and
.I stderr
is granted.
.SH SEE ALSO
.BR busybox (1),
.BR sh (1),
.BR yom (1)