[−][src]Struct subprocess::Pipeline
A builder for multiple Popen
instances connected via
pipes.
A pipeline is a sequence of two or more Exec
commands
connected via pipes. Just like in a Unix shell pipeline, each
command receives standard input from the previous command, and
passes standard output to the next command. Optionally, the
standard input of the first command can be provided from the
outside, and the output of the last command can be captured.
In most cases you do not need to create Pipeline
instances
directly; instead, combine Exec
instances using the |
operator which produces Pipeline
.
Examples
Execute a pipeline and return the exit status of the last command:
let exit_status = (Exec::shell("ls *.bak") | Exec::cmd("xargs").arg("rm")).join()?;
Capture the pipeline's output:
let dir_checksum = { Exec::cmd("find . -type f") | Exec::cmd("sort") | Exec::cmd("sha1sum") }.capture()?.stdout_str();
Methods
impl Pipeline
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pub fn new(cmd1: Exec, cmd2: Exec) -> Pipeline
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Creates a new pipeline by combining two commands.
Equivalent to cmd1 | cmd2
.
pub fn stdin<T: Into<InputRedirection>>(self, stdin: T) -> Pipeline
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Specifies how to set up the standard input of the first command in the pipeline.
Argument can be:
- a
Redirection
; - a
File
, which is a shorthand forRedirection::File(file)
; - a
Vec<u8>
or&str
, which will set up aRedirection::Pipe
for stdin, making sure thatcapture
feeds that data into the standard input of the subprocess. NullFile
, which will redirect the standard input to read from /dev/null.
pub fn stdout<T: Into<OutputRedirection>>(self, stdout: T) -> Pipeline
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Specifies how to set up the standard output of the last command in the pipeline.
Argument can be:
- a
Redirection
; - a
File
, which is a shorthand forRedirection::File(file)
; NullFile
, which will redirect the standard output to write to /dev/null.
pub fn stderr_to(self, to: File) -> Pipeline
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Specifies a file to which to redirect the standard error of all the commands in the pipeline.
It is useful for capturing the standard error of the pipeline as a
whole. Unlike stdout()
, which only affects the last command in
the pipeline, this affects all commands. The difference is
because standard output is piped from one command to the next, so
only the output of the last command is "free". In contrast, the
standard errors are not connected in any way. This is also the
reason only a File
is supported - it allows for efficient
sharing of the same file by all commands.
pub fn popen(self) -> PopenResult<Vec<Popen>>
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Starts all commands in the pipeline, and returns a
Vec<Popen>
whose members correspond to running commands.
If some command fails to start, the remaining commands
will not be started, and the appropriate error will be
returned. The commands that have already started will be
waited to finish (but will probably exit immediately due
to missing output), except for the ones for which
detached()
was called. This is equivalent to what the
shell does.
pub fn join(self) -> PopenResult<ExitStatus>
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Starts the pipeline, waits for it to finish, and returns the exit status of the last command.
pub fn stream_stdout(self) -> PopenResult<impl Read>
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Starts the pipeline and returns a value implementing the Read
trait that reads from the standard output of the last command.
This will automatically set up
stdout(Redirection::Pipe)
, so it is not necessary to do
that beforehand.
When the trait object is dropped, it will wait for the
pipeline to finish. If this is undesirable, use
detached()
.
pub fn stream_stdin(self) -> PopenResult<impl Write>
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Starts the pipeline and returns a value implementing the Write
trait that writes to the standard input of the last command.
This will automatically set up stdin(Redirection::Pipe)
,
so it is not necessary to do that beforehand.
When the trait object is dropped, it will wait for the
process to finish. If this is undesirable, use
detached()
.
pub fn capture(self) -> PopenResult<CaptureData>
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Starts the pipeline, collects its output, and waits for all commands to finish.
The return value provides the standard output of the last command, the combined standard error of all commands, and the exit status of the last command. The captured outputs can be accessed as bytes or strings.
Unlike Popen::communicate
, this method actually waits for the
processes to finish, rather than simply waiting for the output to
close. If this is undesirable, use detached()
.
Trait Implementations
impl BitOr<Exec> for Pipeline
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type Output = Pipeline
The resulting type after applying the |
operator.
fn bitor(self, rhs: Exec) -> Pipeline
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Append a command to the pipeline and return a new pipeline.
impl BitOr<Pipeline> for Pipeline
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type Output = Pipeline
The resulting type after applying the |
operator.
fn bitor(self, rhs: Pipeline) -> Pipeline
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Append a pipeline to the pipeline and return a new pipeline.
impl Clone for Pipeline
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fn clone(&self) -> Pipeline
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Returns a copy of the value.
This method is guaranteed not to fail as long as none of
the Redirection
values contain a Redirection::File
variant. If a redirection to File
is present, cloning
that field will use File::try_clone
method, which
duplicates a file descriptor and can (but is not likely
to) fail. In that scenario, Exec::clone
panics.
fn clone_from(&mut self, source: &Self)
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impl Debug for Pipeline
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Auto Trait Implementations
impl !RefUnwindSafe for Pipeline
impl !Send for Pipeline
impl !Sync for Pipeline
impl Unpin for Pipeline
impl UnwindSafe for Pipeline
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
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impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> ToOwned for T where
T: Clone,
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T: Clone,
type Owned = T
The resulting type after obtaining ownership.
fn to_owned(&self) -> T
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fn clone_into(&self, target: &mut T)
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impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,