## Command Reference
| [`WORKDIR`](#workdir) | `WORKDIR <path>` |
| [`WORKSPACE`](#workspace) | `WORKSPACE SNAPSHOT\|LOCAL` |
| [`ENV`](#env) | `ENV KEY=value` |
| [`INHERIT_ENV`](#inherit_env) | `INHERIT_ENV <key>...` |
| [`ECHO`](#echo) | `ECHO <message>` |
| [`RUN`](#run) | `RUN <command...> \| RUN ["exe", "arg", ...]` |
| [`COPY`](#copy) | `COPY [--from-current-workspace] <from> <to>` |
| [`COPY_GIT`](#copy_git) | `COPY_GIT [--include-dirty] <rev> <src> <dst>` |
| [`SYMLINK`](#symlink) | `SYMLINK <from> <to>` |
| [`MKDIR`](#mkdir) | `MKDIR <path>` |
| [`LS`](#ls) | `LS [<path>]` |
| [`CWD`](#cwd) | `CWD` |
| [`READ`](#read) | `READ [<path>]` |
| [`READ_LINE`](#read_line) | `READ_LINE $var` |
| [`WRITE`](#write) | `WRITE <path> [<contents>]` |
| [`APPEND`](#append) | `APPEND <path> [<contents>]` |
| [`EXPAND`](#expand) | `EXPAND [<path>] [<KEY=val> ...]` |
| [`ASSERT_EQ`](#assert_eq) | `ASSERT_EQ [--hash <sha256>] <actual> <expected>` |
| [`ASSERT_CONTAINS`](#assert_contains) | `ASSERT_CONTAINS <haystack> <needle>` |
| [`HASH_SHA256`](#hash_sha256) | `HASH_SHA256 <path>` |
| [`EXIT`](#exit) | `EXIT <code>` |
| [`SLEEP`](#sleep) | `SLEEP <duration>` |
| [`WITH_IO`](#with_io) | `WITH_IO [<stream>[=pipe:<name>\|=$var], ...] <command> \| WITH_IO [bindings] { <commands> }` |
| [`FOR`](#for) | `FOR $item: TYPE IN <expr> { <commands> } \| FOR $key: STRING, $value: TYPE IN <expr> { <commands> }` |
| [`IF`](#if) | `IF <expr> { <commands> } [ELSE IF <expr> { <commands> }] [ELSE { <commands> }]` |
| [`LET`](#let) | `LET $var: TYPE = <expr> \| LET $var: TYPE = ASYNC { <commands> } \| LET $var: TYPE = <command> \| LET $var: TYPE = AWAIT $task` |
| [`MUTATION`](#mutation) | `$var = <expr>` |
| [`ASYNC`](#async) | `ASYNC <command...> \| ASYNC { <commands> } \| LET $var: HANDLE = ASYNC { <commands> }` |
| [`AWAIT`](#await) | `AWAIT $var \| LET $out: STRING = AWAIT $var` |
| [`CANCEL`](#cancel) | `CANCEL $var` |
| [`TIMEOUT`](#timeout) | `TIMEOUT <duration> <command...> \| TIMEOUT <duration> { <commands> } \| TIMEOUT <duration> AWAIT $var` |
| [`FUNC`](#func) | `FUNC NAME($param: TYPE, ...) { <commands> }` |
| [`CALL`](#call) | `CALL NAME(<expr>, ...) \| LET $var: TYPE = CALL NAME(<expr>, ...)` |
| [`RETURN`](#return) | `RETURN <expr>` |
| [`WHILE`](#while) | `WHILE <bool-expr> { <commands> }` |
| [`BREAK`](#break) | `BREAK` |
| [`CONTINUE`](#continue) | `CONTINUE` |
### WITH_IO
Reroute standard streams.
**Syntax:** `WITH_IO [<stream>[=pipe:<name>|=$var], ...] <command> | WITH_IO [bindings] { <commands> }`
Reroutes the standard streams of the next command or, in block form,
of every enclosed command.
Bindings map streams (`stdin`, `stdout`, `stderr`) to named script
pipes (`stdout=pipe:name`, `stderr=pipe:name`) or to a PIPE-typed
variable (`stdin=$p`, resolved against the live pipe registry when
the step runs). Both stdout and stderr pipes capture output the same way.
Pipes hold bytes in memory and spill to a temp file above 8 MiB, so a
producer can finish before the consumer starts.
If WITH_IO wraps an ASYNC block whose body is a single RUN, guarded or
not, the pipe is a zero copy OS kernel pipe instead: pair it with a
consumer that runs while the producer is alive, since output past the
64 KiB kernel buffer stalls until drained. That promotion never crosses
a CALL boundary: pipes created, bound, or passed by variable inside FUNC
bodies are always script pipes, even when the surrounding task would
otherwise promote.
A second producer or consumer on a live name is an explicit error. A name
bound as output can later feed another command's `stdin`, connecting
commands without touching the terminal. Binding `stdout` and `stderr` to
the same live pipe name fails deterministically. Merge streams in shell
via `2>&1` instead.
Nested blocks stack defaults; inline bindings override inherited ones for
their command only; closing a block restores previous wiring.
**Examples:**
**Example: with_io block**
```oxdock
WITH_IO [stdout=pipe:log] {
ECHO first
ECHO second
}
WITH_IO [stdin=pipe:log] WRITE captured.txt
```
**Example: variable pipe binding**
```oxdock
# Declare the pipe first with the explicit handle operator
# (like `env:KEY`): `pipe:log` names a pipe without touching
# a stream. A plain string here would be a TypeMismatch.
# `$p` (not `pipe:$p`) is the variable form; literals stay
# `pipe:name`.
LET $p: PIPE = pipe:log
WITH_IO [stdout=$p] ECHO hello
WITH_IO [stdin=$p] READ_LINE $line
ASSERT_EQ $line "hello"
```
### FOR
Iterate over a list or map.
**Syntax:** `FOR $item: TYPE IN <expr> { <commands> } | FOR $key: STRING, $value: TYPE IN <expr> { <commands> }`
The loop variable receives each element (lists) or value (maps); with
two variables, the first receives the key.
Loop variables are declared with explicit types and scoped per iteration;
they do not leak outward. The body may be a braced block
or a single-line `{ ... }` command.
`GLOB("...")` patterns must be quoted (`*` is not a bare word, so
`GLOB(*)` is a parse error); GLOB returns a root-relative sorted list,
empty when nothing matches, and rejects `..` escapes.
**Examples:**
**Example: for loop**
```oxdock
LET $items: LIST = ["a", "b"]
FOR $item: STRING IN $items {
ECHO $item
}
LET $map: MAP = {"x": 1}
FOR $k: STRING, $v: INT IN $map {
ECHO "$k=$v"
}
```
**Example: expand every match**
```oxdock
# single-line body; $x is a template path, WHO an override
WRITE a.txt "hi \{{ env:WHO }}!"
FOR $x: STRING IN GLOB("*.txt") { EXPAND $x WHO=World }
ASSERT_CONTAINS stdout "hi World!"
```
### IF
Conditional execution.
**Syntax:** `IF <expr> { <commands> } [ELSE IF <expr> { <commands> }] [ELSE { <commands> }]`
The condition is evaluated as a boolean expression.
Prefix `!` negates (`IF !false`); `&&` binds tighter than
`||`, and both short-circuit, so `IF true || $missing`
never evaluates the right side. Only Bool values are
accepted as conditions.
**Examples:**
**Example: if else**
```oxdock
IF true {
WRITE yes.txt taken
} ELSE {
WRITE yes.txt skipped
}
IF false {
WRITE skipped.txt no
} ELSE IF true {
WRITE fallback.txt taken
}
# !false evaluates to true, so this branch runs.
IF !false {
WRITE negated.txt taken
}
LET $yes_body: STRING = READ yes.txt
LET $fallback_body: STRING = READ fallback.txt
LET $negated_body: STRING = READ negated.txt
ASSERT_EQ $yes_body "taken"
ASSERT_EQ $fallback_body "taken"
ASSERT_EQ $negated_body "taken"
LET $t: STRING = PATH_TYPE("skipped.txt")
ASSERT_EQ $t "absent"
```
**Example: logical condition composition**
```oxdock
LET $role: STRING = "admin"
LET $level: INT = 3
# || is true when either side holds; && needs both.
} ELSE {
WRITE fallback.txt or-false
}
}
IF $role == "admin" && $level >= 5 {
WRITE unexpected-too.txt no
} ELSE {
WRITE and.txt and-false
}
LET $fb: STRING = READ fallback.txt
LET $ch: STRING = READ chosen.txt
LET $an: STRING = READ and.txt
ASSERT_EQ $fb "or-false"
ASSERT_EQ $ch "or-true"
ASSERT_EQ $an "and-false"
LET $t1: STRING = PATH_TYPE("unexpected.txt")
LET $t2: STRING = PATH_TYPE("unexpected-too.txt")
ASSERT_EQ $t1 "absent"
ASSERT_EQ $t2 "absent"
```
### LET
Bind script-local variables.
**Syntax:** `LET $var: TYPE = <expr> | LET $var: TYPE = ASYNC { <commands> } | LET $var: TYPE = <command> | LET $var: TYPE = AWAIT $task`
Declares a script-local variable with an explicit type (STRING, INT,
FLOAT, BOOL, PIPE, LIST, MAP, HANDLE, DURATION, PATH). Duplicate LET
in the same scope frame is a redeclaration error; mutate with
`$var = <expr>`.
Variables are usable in templates (`{{ $var }}`), guards, and
expressions. With `ASYNC`, spawns a background task and stores its
handle (see ASYNC). The `$` sigil on the name is mandatory.
The right-hand side is always an expression — literals, lists, maps,
arithmetic (`+ - * /` with `*`/`/` binding tighter, unary `-`,
parentheses), comparisons (`< <= > >=` binding tighter than
`== !=`), logical `&&` (tighter) and `||` with short-circuit,
`!` negation, `env:KEY` reads, `pipe:NAME` handles,
`INSPECT($var)` snapshots, `GLOB("*.md")`, `INT(x)` /
`FLOAT(x)` conversions — never a `{{ ... }}` template;
interpolation happens in string values, not here.
Numbers are numeric literals: `42` binds `INT`, `3.14` binds
`FLOAT`. `Int x Int` stays `INT` (checked, integer division,
so `7 / 2` is `3`); any `Float` operand promotes to `FLOAT`.
Division by zero, overflow, and non-finite results are errors.
Both numeric sides compare numerically (`1 == 1.0` is true);
otherwise `==`/`!=` compare rendered strings and ordering on
non-numerics is a Type Error. Constant subtrees fold at parse
time and dynamic arithmetic compiles to flat RPN with
identical semantics.
Float equality is exact with no epsilon. Floats store decimals
in binary, so a value is exact only when its reduced fraction
has a power-of-2 denominator: 0.5 (1/2), 0.25 (1/4), 0.75
(3/4) are exact, while 0.1 (1/10), 0.2 (1/5), 0.3 (3/10)
repeat forever in binary (like 1/3 in decimal) and truncate,
so `0.1 + 0.2 == 0.3` is false (the sum is
`0.30000000000000004`). Rule of thumb: endings .5, .25, .75,
.125, .625, .875 are exact; .1, .2, .3 and similar are
approximations. Bound approximations instead of comparing
them: `IF $sum > 0.299999 && $sum < 0.300001`.
Comparisons do not chain: `a < b < c` is a parse error, not
`(a < b) < c`. Chaining would compare a `BOOL` against a
number (a runtime Type Error in C-style parsing) or evaluate
the middle term twice (Python-style chaining), so the grammar
accepts exactly one comparison operator per level. Write the
conjunction explicitly: `$a < $b && $b < $c`. The same holds
for equality (`$a == $b == $c` is rejected).
Captured command output is a string, so convert before math:
`LET $total: INT = $total + INT($size_str)` (`INT` trims ASCII
whitespace; `FLOAT` accepts int strings and rejects
non-finite).
Bare words need no quotes: `LET $d: STRING = 30s` binds the same string
as quoted.
When the right-hand side is a synchronous command
(`LET $out: STRING = ECHO hi`), the command runs to completion and its
exact stdout bytes are captured into the variable as a string (no newline
stripping; commands with no stdout capture as `""`; non-UTF8 stdout is
an error). Combining capture with an explicit
`WITH_IO [stdout=pipe:...]` is a parse error.
Coming from Bash, the capture line looks familiar but behaves
strictly:
| Trailing newlines | Stripped (all of them) | Preserved byte-exact |
| Variable type | Always an untyped string | Declared: STRING, INT, FLOAT, ... |
| Math on output | Implicit: `$((var + 1))` | Explicit: `INT($out) + 1` |
| Failing command | Continues with empty output unless `set -e` | Step fails immediately, binds nothing |
`LET $out: STRING = AWAIT $var` captures a background task's stdout the
same way; bare `AWAIT $var` forwards it to the parent stdout instead.
`LET $e: STRING = env:FOO` reads the script environment into a plain
string.
**Examples:**
**Example: let**
```oxdock
LET $name: STRING = "world"
ECHO "hello, {{ $name }}"
LET $items: LIST = ["a", "b"]
LET $count: INT = 42
```
**Example: glob binding**
```oxdock
# the RHS is an expression: GLOB(...) runs and binds a list
WRITE a.txt "x"
LET $files: LIST = GLOB("*.txt")
FOR $f: STRING IN $files { ECHO $f }
ASSERT_CONTAINS stdout "a.txt"
```
**Example: scoped variable reverts**
```oxdock
# LET inside a braced block reverts when the block exits
LET $a: STRING = "outer"
[bool:true] {
LET $a: STRING = "inner"
WRITE inner.txt "{{ $a }}"
}
WRITE outer.txt "{{ $a }}"
LET $in_body: STRING = READ inner.txt
LET $out_body: STRING = READ outer.txt
ASSERT_EQ $in_body "inner"
ASSERT_EQ $out_body "outer"
```
**Example: capture command output**
```oxdock
LET $out: STRING = ECHO hi
ASSERT_EQ $out "hi\n"
```
**Example: arithmetic over captured output**
```oxdock
LET $size_str: STRING = ECHO 41
LET $total: INT = INT($size_str) + 1
LET $ratio: FLOAT = 1 + 2.5
# Int x Int stays INT: integer division truncates.
LET $half: INT = 7 / 2
ASSERT_EQ $total 42
ASSERT_EQ $ratio 3.5
ASSERT_EQ $half 3
```
**Example: float equality is exact**
```oxdock
# Binary fractions compare cleanly; decimal fractions may not:
# 0.1 + 0.2 is 0.30000000000000004, so == is false.
LET $exact: BOOL = 0.5 + 0.25 == 0.75
LET $decimal: BOOL = 0.1 + 0.2 == 0.3
IF $exact {
WRITE exact.txt yes
}
IF $decimal {
WRITE unexpected.txt no
}
LET $ok: STRING = READ exact.txt
ASSERT_EQ $ok "yes"
LET $t: STRING = PATH_TYPE("unexpected.txt")
ASSERT_EQ $t "absent"
```
**Example: bound inexact decimals**
```oxdock
# Never test inexact decimals for equality; bound them.
LET $sum: FLOAT = 0.1 + 0.2
IF $sum > 0.299999 && $sum < 0.300001 {
WRITE bounded.txt yes
}
LET $ok: STRING = READ bounded.txt
ASSERT_EQ $ok "yes"
```
**Example: inspect a variable**
```oxdock
# INSPECT($var) snapshots a variable into a MAP: declared
# type plus live details (pipe backend stats here), so
# scripts can branch on engine state.
LET $p: PIPE = pipe:log
WITH_IO [stdout=$p] ECHO hello
LET $info: MAP = INSPECT($p)
IF $info.is_os_pipe {
WRITE unexpected.txt "should be a script pipe"
}
ASSERT_EQ $info.type "PIPE"
```
### MUTATION
Mutate a declared variable.
**Syntax:** `$var = <expr>`
Reassigns an existing variable, converting the new value to
the type declared at LET time. The explicit annotation is
what authorizes string-to-number conversion here (`$n = "42"`
binds 42 for an INT); a non-numeric string is an error.
Expressions never convert: `"100" + 1` is a Type Error, use
`INT()` / `FLOAT()` to cross that boundary explicitly.
The leading `$` distinguishes mutation from `KEY=value` command
assignments. Assigning an undeclared variable or a mismatched type is
an error.
Mutation writes through to the scope where the variable was
declared, so it survives block exit: `LET $x` outside a block
followed by `$x = ...` inside still reads back the new value
afterwards, for every type. This is the counterpart to LET
shadowing, where `LET $x` *inside* the block declares a
separate inner variable that reverts on exit.
**Examples:**
**Example: mutate**
```oxdock
LET $count: INT = 1
$count = 2
ASSERT_EQ $count 2
```
**Example: convert before math**
```oxdock
# Captured output is a string: `"100" + 1` is a Type Error.
# Convert explicitly, then mutate with arithmetic.
LET $raw: STRING = ECHO 100
LET $n: INT = INT($raw)
$n = $n + 1
# The declared type also converts plain strings on assignment.
$n = "42"
# Same crossing for decimals via FLOAT().
LET $frac_str: STRING = ECHO 2.5
LET $f: FLOAT = FLOAT($frac_str) + 0.25
ASSERT_EQ $n 42
ASSERT_EQ $f 2.75
```
### ASYNC
Run steps in a background thread.
**Syntax:** `ASYNC <command...> | ASYNC { <commands> } | LET $var: HANDLE = ASYNC { <commands> }`
Runs a command or block of commands in a background thread with
subshell isolation.
Mutations (ENV, WORKDIR) stay within the block. With `LET`, stores a
task handle for `AWAIT`.
**Examples:**
**Example: async**
```oxdock
ASYNC ECHO "first"
ASYNC {
ECHO "first"
ECHO "second"
}
```
**Example: async task handle**
```oxdock
LET $task: HANDLE = ASYNC {
ECHO "built"
}
AWAIT $task
```
### AWAIT
Join a background task.
**Syntax:** `AWAIT $var | LET $out: STRING = AWAIT $var`
Blocks until the named task completes. Propagates errors if the task failed.
Bare `AWAIT $var` forwards the task's stdout to the parent stdout;
`LET $out: STRING = AWAIT $var` captures it into `$out` instead (same
UTF-8 and spilling rules as `LET $var: STRING = <command>`).
**Examples:**
**Example: await**
```oxdock
LET $task: HANDLE = ASYNC ECHO "done"
AWAIT $task
```
**Example: await capture**
```oxdock
LET $task: HANDLE = ASYNC ECHO "done"
LET $out: STRING = AWAIT $task
ASSERT_EQ $out "done\n"
```
### CANCEL
Synchronously cancel a background task.
**Syntax:** `CANCEL $var`
Kills the named background task spawned via LET $var: HANDLE = ASYNC ....
Blocking: returns only after the task thread has been joined and its OS
process reaped, so no residual filesystem or stream mutation follows. A
later AWAIT $var reports cancellation. Only named tasks can be cancelled.
**Examples:**
**Example: cancel**
```oxdock
LET $task: HANDLE = ASYNC SLEEP 30s
CANCEL $task
```
### TIMEOUT
Enforce an execution deadline.
**Syntax:** `TIMEOUT <duration> <command...> | TIMEOUT <duration> { <commands> } | TIMEOUT <duration> AWAIT $var`
Aborts the wrapped step or block with a deadline error if it exceeds the
duration (e.g. 500ms, 10s, 2m; a bare number means seconds).
A blocking foreground process is killed.
**Examples:**
**Example: timeout**
```oxdock
TIMEOUT 30s WRITE heartbeat.txt alive
```
**Example: timeout block**
```oxdock
TIMEOUT 30s {
WRITE a.txt one
WRITE b.txt two
}
```
**Example: timeout variable duration**
```oxdock
# durations resolve at runtime, so variables work too
LET $budget: DURATION = "30s"
TIMEOUT $budget WRITE heartbeat.txt alive
LET $beat: STRING = READ heartbeat.txt
ASSERT_EQ $beat "alive"
```
### FUNC
Define a user function.
**Syntax:** `FUNC NAME($param: TYPE, ...) { <commands> }`
Defines a user function with UPPERCASE name and explicitly typed
parameters.
Params bind by position, converting each argument to its
declared parameter type before the body runs.
Bodies run in a fresh variable scope; LETs inside do not leak. A nested
FUNC definition is scoped to its block and reverts on exit. Names share
one namespace with host-registered functions.
**Examples:**
**Example: func def call**
```oxdock
FUNC GREET($name: STRING) {
RETURN $name
}
LET $res: STRING = CALL GREET("ada")
ASSERT_EQ $res "ada"
```
### CALL
Invoke a user or host function.
**Syntax:** `CALL NAME(<expr>, ...) | LET $var: TYPE = CALL NAME(<expr>, ...)`
Invokes a FUNC-defined or host-registered function by UPPERCASE name.
Bare CALL discards the return value and keeps stdout side effects.
LET $var: TYPE = CALL captures the RETURN value (fallthrough without
RETURN captures as ""), coerced to the declared type; stdout inside the
callee stays observable via ASSERT_CONTAINS stdout and pipes.
Combining LET-capture with WITH_IO [stdout=pipe:...] is a parse error.
**Examples:**
**Example: call**
```oxdock
FUNC SHOUT($name: STRING) {
ECHO "{{ $name }}"
RETURN $name
}
CALL SHOUT("ada")
ASSERT_CONTAINS stdout "ada"
```
**Example: call with pipes**
```oxdock
# A pipe handle travels into a function as a typed argument
# and is usable as a binding target in both directions.
# `pipe:ch` constructs the handle; `$p` passes it on.
FUNC DRAIN($q: PIPE) {
WITH_IO [stdin=$q] READ_LINE $line
RETURN $line
}
LET $p: PIPE = pipe:ch
WITH_IO [stdout=$p] ECHO "payload"
LET $got: STRING = CALL DRAIN($p)
ASSERT_EQ $got "payload"
```
### RETURN
Return a value from a function.
**Syntax:** `RETURN <expr>`
Ends the nearest enclosing function call with a value.
Falling off the end without RETURN yields "". RETURN outside a function
(including at top level or across an ASYNC boundary) is an error.
**Examples:**
**Example: return**
```oxdock
FUNC PICK($flag: BOOL) {
IF $flag {
RETURN "yes"
}
RETURN "no"
}
LET $res: STRING = CALL PICK(true)
ASSERT_EQ $res "yes"
```
### WHILE
Loop while a condition holds.
**Syntax:** `WHILE <bool-expr> { <commands> }`
Re-evaluates a Bool condition each iteration (same is_truthy rule as IF;
non-Bool is a type error).
Each iteration runs in a fresh scope; mutate outer state with $var = ...
so the next check observes it. BREAK exits the loop; CONTINUE skips to
the next check.
**Examples:**
**Example: while loop**
```oxdock
LET $done: BOOL = false
WHILE !$done {
WRITE tick.txt "once"
$done = true
}
LET $tick: STRING = READ tick.txt
ASSERT_EQ $tick "once"
```
### BREAK
Exit the innermost loop.
**Syntax:** `BREAK`
Exits the innermost enclosing FOR or WHILE loop.
BREAK outside a loop, or across a FUNC or ASYNC boundary, is an error.
**Examples:**
**Example: break**
```oxdock
FOR $x: STRING IN ["a", "b"] {
BREAK
}
```
### CONTINUE
Skip to the next loop iteration.
**Syntax:** `CONTINUE`
Skips the rest of the innermost enclosing FOR or WHILE body and starts
the next iteration.
CONTINUE outside a loop, or across a FUNC or ASYNC boundary, is an error.
**Examples:**
**Example: continue**
```oxdock
FOR $x: STRING IN ["a", "b"] {
CONTINUE
}
```
### WORKDIR
Change the working directory.
**Syntax:** `WORKDIR <path>`
Sets the current working directory.
Relative paths resolve against the current directory; `/` resets to
the workspace root. Paths cannot escape the workspace.
**Arguments:**
| `path` | [`PATH`](#value-type-path) | yes | Directory to change to |
**Examples:**
**Example: change working directory**
```oxdock
WORKDIR project/src
WRITE generated.txt generated-under-workdir
LET $body: STRING = READ generated.txt
ASSERT_EQ $body "generated-under-workdir"
```
### WORKSPACE
Switch workspace roots.
**Syntax:** `WORKSPACE SNAPSHOT|LOCAL`
SNAPSHOT or LOCAL root.
**Arguments:**
| `target` | `SNAPSHOT\|LOCAL` | yes | Target root |
**Examples:**
**Example: switch roots**
```oxdock
WORKSPACE LOCAL
```
### ENV
Set an environment variable.
**Syntax:** `ENV KEY=value`
Inserts or updates an env var.
The value uses the unified string-value rules shared by every command:
`"..."` or `'...'` quotes keep exact bytes (spaces, tabs), a lone `$var`
evaluates that variable, `{{ ... }}` placeholders interpolate, unquoted
words join with single spaces, and the first `=` splits key from value
(`KEY=a=b` stores `a=b`).
A `$var` inside larger text stays literal — write `{{ $var }}` to
interpolate there.
**Arguments:**
| `assignment` | `STRING` | yes | KEY=value pair; the value resolves as STRING |
**Examples:**
**Example: set env**
```oxdock
ENV APP_MODE=production
```
**Example: quoted value with spaces**
```oxdock
# quotes keep the space: SET_FORTH stores `outer scope`
ENV SET_FORTH="outer scope"
WRITE out.txt "{{ env:SET_FORTH }}"
LET $body: STRING = READ out.txt
ASSERT_EQ $body "outer scope"
```
**Example: variable value**
```oxdock
# a lone $var evaluates, like ECHO $var
LET $who: STRING = "Alice"
ENV GREETING=$who
WRITE out.txt "{{ env:GREETING }}"
LET $body: STRING = READ out.txt
ASSERT_EQ $body "Alice"
```
**Example: all value forms agree**
```oxdock
# a bare variable, a quoted literal, and a template all
# store plain strings through the same value rules
LET $x: STRING = "Ada"
ENV A=$x
ENV B="hello world"
ENV C="{{ $x }} concatenated"
ASSERT_EQ $body "Ada|hello world|Ada concatenated"
```
**Example: scoped env reverts**
```oxdock
# ENV inside a braced block reverts when the block exits
ENV MODE=production
[bool:true] {
ENV MODE=staging
WRITE inner.txt "{{ env:MODE }}"
}
WRITE outer.txt "{{ env:MODE }}"
LET $inner_body: STRING = READ inner.txt
LET $outer_body: STRING = READ outer.txt
ASSERT_EQ $inner_body "staging"
ASSERT_EQ $outer_body "production"
```
### INHERIT_ENV
Inherit env vars from host.
**Syntax:** `INHERIT_ENV <key>...`
Declares which host environment variables to inherit into the script.
Must appear before any other commands and at most once. Without this
directive, the script starts with an empty environment.
**Arguments:**
| `keys` | [`STRING...`](#value-type-string) | no | Host variables to inherit |
**Examples:**
**Example: inherit env**
```oxdock
INHERIT_ENV [PATH, HOME]
```
### ECHO
Print to stdout.
**Syntax:** `ECHO <message>`
Outputs message to stdout.
**Arguments:**
| `message` | [`STRING...`](#value-type-string) | yes | Text |
**Output:** Stdout
**Examples:**
**Example: echo**
```oxdock
ECHO build-complete
```
**Example: variables**
```oxdock
# a lone $x evaluates; {{ }} interpolates inside text
LET $x: STRING = "World"
ECHO {{ $x }}
ECHO $x
ASSERT_CONTAINS stdout "World"
```
### RUN
Execute shell command or direct executable.
**Syntax:** `RUN <command...> | RUN ["exe", "arg", ...]`
Shell form (`RUN <command...>`) runs the joined command string in the
system shell (`$SHELL -c` / `COMSPEC /C`).
Exec form (`RUN ["exe", "arg", ...]`) spawns the executable directly
with no shell, so there is no shell expansion, globbing, redirection,
or pipes; use it for portable commands.
Guards and wrappers (`ASYNC`, `TIMEOUT`, `WITH_IO`, `LET`) apply to
both forms.
**Arguments:**
| `command` | [`STRING...`](#value-type-string) | yes | Command |
**Examples:**
**Example: run**
```oxdock
RUN echo hello
```
**Example: run exec form**
```oxdock
RUN ["cargo", "--version"]
```
### COPY
Copy file into workspace.
**Syntax:** `COPY [--from-current-workspace] <from> <to>`
Copies from host.
**Arguments:**
| `from` | [`PATH`](#value-type-path) | yes | Source |
| `to` | [`PATH`](#value-type-path) | yes | Dest |
**Flags:**
| `--from-current-workspace` | `BOOL` | Copy from workspace instead of build context |
**Examples:**
**Example: copy**
```oxdock roots:unified
WRITE src.txt content
COPY src.txt dst.txt
LET $body: STRING = READ dst.txt
ASSERT_EQ $body "content"
```
**Example: copy from workspace**
```oxdock roots:unified
WRITE ws-src.txt ws-content
COPY --from-current-workspace ws-src.txt ws-copy.txt
LET $body: STRING = READ ws-copy.txt
ASSERT_EQ $body "ws-content"
```
### COPY_GIT
Copy from git revision.
**Syntax:** `COPY_GIT [--include-dirty] <rev> <src> <dst>`
Checkout and copy.
**Arguments:**
| `rev` | [`STRING`](#value-type-string) | yes | Rev |
| `src` | [`PATH`](#value-type-path) | yes | Src |
| `dst` | [`PATH`](#value-type-path) | yes | Dst |
**Flags:**
| `--include-dirty` | `BOOL` | Include dirty |
**Examples:**
**Example: git copy**
```oxdock expect_error:"COPY source missing"
COPY_GIT HEAD src.txt dst.txt
```
### SYMLINK
Create symlink.
**Syntax:** `SYMLINK <from> <to>`
Creates symlink.
**Arguments:**
| `from` | [`PATH`](#value-type-path) | yes | Target |
| `to` | [`PATH`](#value-type-path) | yes | Link |
**Examples:**
**Example: symlink**
```oxdock roots:unified
WRITE original.txt content
SYMLINK original.txt link.txt
LET $body: STRING = READ link.txt
ASSERT_EQ $body "content"
```
### MKDIR
Create directory.
**Syntax:** `MKDIR <path>`
Creates dir with parents.
**Arguments:**
| `path` | [`PATH`](#value-type-path) | yes | Dir path |
**Examples:**
**Example: mkdir**
```oxdock
MKDIR deeply/nested/tree
```
### LS
List directory.
**Syntax:** `LS [<path>]`
Lists entries.
**Arguments:**
| `path` | [`PATH`](#value-type-path) | no | Dir |
**Output:** Stdout
**Examples:**
**Example: ls**
```oxdock
MKDIR inventory
WRITE inventory/a.txt a
LS inventory
```
### CWD
Print working directory.
**Syntax:** `CWD`
Outputs cwd.
**Output:** Stdout
**Examples:**
**Example: cwd**
```oxdock
CWD
```
### READ
Read file to stdout.
**Syntax:** `READ [<path>]`
Outputs file contents.
**Arguments:**
| `path` | [`PATH`](#value-type-path) | no | File |
**Output:** Stdout
**Examples:**
**Example: read**
```oxdock
WRITE note.txt "hello"
READ note.txt
```
### READ_LINE
Read one line from stdin into a variable.
**Syntax:** `READ_LINE $var`
Reads bytes until newline without waiting for EOF, leaving the pipe open.
Trailing newline is stripped (shell-read parity). On premature EOF
assigns accumulated bytes and returns.
**Arguments:**
| `var` | `STRING` | yes | Target variable (`$name`); the line binds as STRING |
**Examples:**
**Example: read line**
```oxdock
WITH_IO [stdout=pipe:lines] ECHO "first"
WITH_IO [stdin=pipe:lines] READ_LINE $reply
```
### WRITE
Write to file.
**Syntax:** `WRITE <path> [<contents>]`
Writes contents.
**Arguments:**
| `path` | [`PATH`](#value-type-path) | yes | File |
| `contents` | [`STRING...`](#value-type-string) | no | Content |
**Examples:**
**Example: write**
```oxdock
WRITE output.txt hello-world
```
### APPEND
Append to file.
**Syntax:** `APPEND <path> [<contents>]`
Appends contents.
**Arguments:**
| `path` | [`PATH`](#value-type-path) | yes | File |
| `contents` | [`STRING...`](#value-type-string) | no | Content |
**Examples:**
**Example: append**
```oxdock
WRITE log.txt line1
APPEND log.txt line2
LET $all: STRING = READ log.txt
ASSERT_EQ $all "line1line2"
```
### EXPAND
Expand a template file (or stdin) to stdout.
**Syntax:** `EXPAND [<path>] [<KEY=val> ...]`
A template is any text file — or piped stdin when no path is given —
containing `{{ ... }}` placeholders. EXPAND replaces each placeholder
and prints the result to stdout.
Placeholders: `{{ NAME }}` reads a `KEY=val` override passed on this
command; `{{ env:NAME }}` reads an override, falling back to the
environment; `{{ $var }}` reads a script variable (dotted paths allowed).
A missing key is an error, never a silent empty.
Substitution runs in a single pass. EXPAND is not recursive and does not
expand nested placeholders: a value that itself contains `{{ ... }}` is
inserted verbatim and never expanded again.
A bare `$var` argument is a template path; `KEY=val` arguments are
overrides whose values follow the unified string-value rules (same as
`ENV`: quotes keep exact bytes, a lone `$var` evaluates,
`{{ ... }}` interpolates).
NOTE: `WRITE` interpolates `{{ ... }}` while writing, so escape it
(`\{{ ... }}`) when writing a template file for a later `EXPAND`.
With no path, the template arrives on stdin through a pipe. When piping
from a shell, single-quote the template (`echo '{{ $x }}'`): double
quotes let the shell swallow `$x`, so oxdock receives an empty `{{ }}`
placeholder and errors.
**Arguments:**
| `path` | [`PATH`](#value-type-path) | no | Template file to expand; omit to expand stdin |
| `overrides` | `STRING...` | no | Template overrides shadowing that key (unified string values) |
**Output:** Stdout
**Examples:**
**Example: expand**
```oxdock
ENV NAME="Alice"
WRITE template.md "Hello {{ env:NAME }}!"
EXPAND template.md
ASSERT_CONTAINS stdout "Hello Alice!"
```
**Example: override with spaces**
```oxdock
# WRITE would interpolate {{ }} right away, so escape it:
# the file must literally contain {{ env:NAME }} for EXPAND
WRITE template.md "Hello \{{ env:NAME }}!"
EXPAND template.md NAME="Alice Smith"
ASSERT_CONTAINS stdout "Hello Alice Smith!"
```
**Example: variable override**
```oxdock
# same escaping: keep the placeholder literal until EXPAND;
# a lone $who evaluates, like ECHO $who
LET $who: STRING = "Bob"
WRITE template.md "Hi \{{ env:WHO }}!"
EXPAND template.md WHO=$who
ASSERT_CONTAINS stdout "Hi Bob!"
```
**Example: override forms agree**
```oxdock
# a bare variable and a template-with-tail expand identically
LET $x: STRING = "Ada"
WRITE template.md "Hi \{{ env:NAME }} and \{{ env:NAME2 }}!"
EXPAND template.md NAME=$x NAME2="{{ $x }} concatenated"
ASSERT_CONTAINS stdout "Hi Ada and Ada concatenated!"
```
**Example: expand stdin**
```oxdock
# no path: the template arrives on stdin through a pipe
WITH_IO [stdout=pipe:tpl] ECHO "Hello \{{ env:NAME }}!"
WITH_IO [stdin=pipe:tpl] EXPAND NAME=Alice
ASSERT_CONTAINS stdout "Hello Alice!"
```
**Example: override does not leak**
```oxdock
# KEY=val overrides shadow env for that EXPAND only —
# they never update the environment itself
ENV NAME="Alice"
WRITE template.md "Hi \{{ env:NAME }}!"
EXPAND template.md NAME="Bob"
ASSERT_CONTAINS stdout "Hi Bob!"
EXPAND template.md
ASSERT_CONTAINS stdout "Hi Alice!"
```
### ASSERT_EQ
Assert strict equality.
**Syntax:** `ASSERT_EQ [--hash <sha256>] <actual> <expected>`
Compares two evaluated values with typed equality (no coercion:
`Int(42)` never equals `String("42")`), aborting the pipeline
with a step-numbered error showing expected vs actual otherwise.
Both sides are values: `$var`, literals, templates, and calls
evaluate in memory and never touch disk. Read files explicitly
first (`LET $text: STRING = READ "out.txt"`, then
`ASSERT_EQ $text ...`).
Bare `stdout` / `stderr` observe stream buffers; `pipe:NAME`
observes a pipe buffer. `--hash` compares the SHA-256 of the
actual's string bytes instead of the bytes themselves.
**Arguments:**
| `actual` | `ANY` | yes | Value, stdout, stderr, or pipe:NAME |
| `expected` | `ANY...` | no | Expected (required unless --hash) |
**Flags:**
| `--hash` | `STRING` | SHA-256 |
**Examples:**
**Example: assert eq**
```oxdock
LET $status: INT = 200
ASSERT_EQ $status 200
```
**Example: assert eq file**
```oxdock
WRITE payload.bin stable-content
LET $body: STRING = READ payload.bin
ASSERT_EQ $body "stable-content"
```
**Example: assert eq hash**
```oxdock
# --hash compares the SHA-256 digest instead of raw bytes
WRITE payload.bin stable-content
LET $body: STRING = READ payload.bin
ASSERT_EQ --hash 08135c1b6349b0e4f894c36221952f0de00e6b4d82f80895abf359755e77103c $body
```
### ASSERT_CONTAINS
Assert containment.
**Syntax:** `ASSERT_CONTAINS <haystack> <needle>`
Checks containment and aborts the pipeline with a step-numbered
error otherwise: substring for strings, element match for lists,
key presence for maps, substring over stream and pipe buffers.
Like `ASSERT_EQ`, both sides are values read without implicit
I/O; read files explicitly first
(`LET $text: STRING = READ "cfg.txt"`).
Bare `stdout` / `stderr` observe stream buffers; `pipe:NAME`
observes a pipe buffer.
**Arguments:**
| `haystack` | `ANY` | yes | Value, stdout, stderr, or pipe:NAME |
| `needle` | `ANY...` | yes | Substring, element, or key |
**Examples:**
**Example: assert contains**
```oxdock
ECHO build-complete
ASSERT_CONTAINS stdout "build-complete"
```
### HASH_SHA256
Print SHA-256.
**Syntax:** `HASH_SHA256 <path>`
Computes digest.
**Arguments:**
| `path` | [`PATH`](#value-type-path) | yes | File |
**Output:** Stdout
**Examples:**
**Example: hash**
```oxdock
WRITE payload.txt hello
HASH_SHA256 payload.txt
```
### EXIT
Exit pipeline.
**Syntax:** `EXIT <code>`
Stops the pipeline immediately with an `EXIT requested with code <code>`
error; steps after it never run, at any nesting depth.
Enclosing blocks still unwind their LET/ENV/WORKDIR/WORKSPACE state,
anonymous background tasks are killed synchronously, and files written
before the EXIT persist.
**Arguments:**
| `code` | [`INT`](#value-type-int) | yes | Code |
**Examples:**
**Example: exit**
```oxdock expect_error:"EXIT requested with code 0"
EXIT 0
```
### SLEEP
Pause execution for a duration.
**Syntax:** `SLEEP <duration>`
Parks the step for the duration (e.g. 500ms, 10s, 2m).
Cooperative: checks for cancellation so an enclosing TIMEOUT or task
teardown interrupts the sleep. Cross-platform alternative to shell sleep
for testing time boundaries.
**Arguments:**
| `duration` | [`DURATION`](#value-type-duration) | yes | How long to sleep |
**Examples:**
**Example: sleep**
```oxdock
SLEEP 100ms
```
**Example: sleep variable duration**
```oxdock
# durations resolve at runtime, so variables work too —
# quoted or bare, both bind the same string
LET $pause: STRING = "100ms"
SLEEP $pause
LET $bare: STRING = 100ms
SLEEP $bare
```
## Value types
### Value type: STRING
Arbitrary text. Quotes keep exact bytes, lone `$var` evaluates, `{{ ... }}` interpolates.
### Value type: INT
64-bit signed integer, e.g. an exit code.
### Value type: FLOAT
64-bit float, e.g. a ratio.
### Value type: BOOL
Boolean `true` or `false`.
### Value type: PIPE
Named script pipe. Validity is checked against the pipe registry at coercion time.
### Value type: LIST
Ordered list of values.
### Value type: MAP
String-keyed map of values.
### Value type: HANDLE
Background ASYNC task handle for AWAIT/CANCEL.
### Value type: DURATION
Positive time span: `500ms`, `10s`, `2m`, `1h`; bare number means seconds.
### Value type: PATH
Workspace path, resolved against cwd and guarded against escape.