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Diffstat (limited to 'src/library/scala/sys/process/ProcessBuilder.scala')
| -rw-r--r-- | src/library/scala/sys/process/ProcessBuilder.scala | 306 |
1 files changed, 219 insertions, 87 deletions
diff --git a/src/library/scala/sys/process/ProcessBuilder.scala b/src/library/scala/sys/process/ProcessBuilder.scala index 214d908012..20270d423f 100644 --- a/src/library/scala/sys/process/ProcessBuilder.scala +++ b/src/library/scala/sys/process/ProcessBuilder.scala @@ -12,133 +12,265 @@ package process import processInternal._ import ProcessBuilder._ -/** Represents a runnable process. +/** Represents a sequence of one or more external processes that can be + * executed. A `ProcessBuilder` can be a single external process, or a + * combination of other `ProcessBuilder`. One can control where a + * the output of an external process will go to, and where its input will come + * from, or leave that decision to whoever starts it. * - * This is the main component of this package. A `ProcessBuilder` may be composed with - * others, either concatenating their outputs or piping them from one to the next, and - * possibly with conditional execution depending on the last process exit value. + * One creates a `ProcessBuilder` through factories provided in + * [[scala.sys.process.Process]]'s companion object, or implicit conversions + * based on these factories made available in the package object + * [[scala.sys.process]]. Here are some examples: + * {{{ + * import.scala.sys.process._ * - * Once executed, one can retrieve the output or redirect it to a - * [[scala.sys.process.ProcessLogger]], or one can get the exit value, discarding or - * redirecting the output. + * // Executes "ls" and sends output to stdout + * "ls".! * - * One creates a `ProcessBuilder` through factories provided in [[scala.sys.process.Process]]'s - * companion object, or implicit conversions based on these factories made available in the - * package object [[scala.sys.process]]. + * // Execute "ls" and assign a `Stream[String]` of its output to "contents". + * // Because [[scala.Predef]] already defines a `lines` method for `String`, + * // we use [[scala.sys.process.Process]]'s object companion to create it. + * val contents = Process("ls").lines * - * Let's examine in detail one example of usage: + * // Here we use a `Seq` to make the parameter whitespace-safe + * def contentsOf(dir: String): String = Seq("ls", dir).!! + * }}} + * + * The methods of `ProcessBuilder` are divided in three categories: the ones that + * combine two `ProcessBuilder` to create a third, the ones that redirect input + * or output of a `ProcessBuilder`, and the ones that execute + * the external processes associated with it. + * + * ==Combining `ProcessBuilder`== + * + * Two existing `ProcessBuilder` can be combined in the following ways: + * + * * They can be executed in parallel, with the output of the first being fed + * as input to the second, like Unix pipes. This is achieved with the `#|` + * method. + * * They can be executed in sequence, with the second starting as soon as + * the first ends. This is done by the `###` method. + * * The execution of the second one can be conditioned by the return code + * (exit status) of the first, either only when it's zero, or only when it's + * not zero. The methods `#&&` and `#||` accomplish these tasks. + * + * ==Redirecting Input/Output== + * + * Though control of input and output can be done when executing the process, + * there's a few methods that create a new `ProcessBuilder` with a + * pre-configured input or output. They are `#<`, `#>` and `#>>`, and may take + * as input either another `ProcessBuilder` (like the pipe described above), or + * something else such as a `java.io.File` or a `java.lang.InputStream`. + * For example: + * {{{ + * new URL("http://databinder.net/dispatch/About") #> "grep JSON" #>> new File("About_JSON") ! + * }}} + * + * ==Starting Processes== + * + * To execute all external commands associated with a `ProcessBuilder`, one + * may use one of four groups of methods. Each of these methods have various + * overloads and variations to enable further control over the I/O. These + * methods are: + * + * * `run`: the most general method, it returns a + * [[scala.sys.process.Process]] immediately, and the external command + * executes concurrently. + * * `!`: blocks until all external commands exit, and returns the exit code + * of the last one in the chain of execution. + * * `!!`: blocks until all external commands exit, and returns a `String` + * with the output generated. + * * `lines`: returns immediately like `run`, and the output being generared + * is provided through a `Stream[String]`. Getting the next element of that + * `Stream` may block until it becomes available. This method will throw an + * exception if the return code is different than zero -- if this is not + * desired, use the `lines_!` method. + * + * ==Handling Input and Output== + * + * If not specified, the input of the external commands executed with `run` or + * `!` will not be tied to anything, and the output will be redirected to the + * stdout and stderr of the Scala process. For the methods `!!` and `lines`, no + * input will be provided, and the output will be directed according to the + * semantics of these methods. * + * Some methods will cause stdin to be used as input. Output can be controlled + * with a [[scala.sys.process.ProcessLogger]] -- `!!` and `lines` will only + * redirect error output when passed a `ProcessLogger`. If one desires full + * control over input and output, then a [[scala.sys.process.ProcessIO]] can be + * used with `run`. + * + * For example, we could silence the error output from `lines_!` like this: + * {{{ + * val etcFiles = "find /etc" lines_! ProcessLogger(line => ()) + * }}} + * + * ==Extended Example== + * + * Let's examine in detail one example of usage: * {{{ * import scala.sys.process._ * "find src -name *.scala -exec grep null {} ;" #| "xargs test -z" #&& "echo null-free" #|| "echo null detected" ! * }}} - * * Note that every `String` is implicitly converted into a `ProcessBuilder` * through the implicits imported from [[scala.sys.process]]. These `ProcessBuilder` are then * combined in three different ways. * * 1. `#|` pipes the output of the first command into the input of the second command. It - * mirrors a shell pipe (`|`). - * 2. `#&&` conditionally executes the second command if the previous one finished with - * exit value 0. It mirrors shell's `&&`. - * 3. `#||` conditionally executes the third command if the exit value of the previous - * command is different than zero. It mirrors shell's `&&`. - * - * Not shown here, the equivalent of a shell's `;` would be `###`. The reason for this name is - * that `;` is a reserved token in Scala. - * - * Finally, `!` at the end executes the commands, and returns the exit value. If the output - * was desired instead, one could run that with `!!` instead. - * - * If one wishes to execute the commands in background, one can either call `run`, which - * returns a [[scala.sys.process.Process]] from which the exit value can be obtained, or - * `lines`, which returns a [scala.collection.immutable.Stream] of output lines. This throws - * an exception at the end of the `Stream` is the exit value is non-zero. To avoid exceptions, - * one can use `lines_!` instead. - * - * One can also start the commands in specific ways to further control their I/O. Using `!<` to - * start the commands will use the stdin from the current process for them. All methods can - * be used passing a [[scala.sys.process.ProcessLogger]] to capture the output, both stderr and - * stdout. And, when using `run`, one can pass a [[scala.sys.process.ProcessIO]] to control - * stdin, stdout and stderr. - * - * The stdin of a command can be redirected from a `java.io.InputStream`, a `java.io.File`, a - * `java.net.URL` or another `ProcessBuilder` through the method `#<`. Likewise, the stdout - * can be sent to a `java.io.OutputStream`, a `java.io.File` or another `ProcessBuilder` with - * the method `#>`. The method `#>>` can be used to append the output to a `java.io.File`. - * For example: + * mirrors a shell pipe (`|`). + * 1. `#&&` conditionally executes the second command if the previous one finished with + * exit value 0. It mirrors shell's `&&`. + * 1. `#||` conditionally executes the third command if the exit value of the previous + * command is different than zero. It mirrors shell's `&&`. * - * {{{ - * new URL("http://databinder.net/dispatch/About") #> "grep JSON" #>> new File("About_JSON") ! - * }}} + * Finally, `!` at the end executes the commands, and returns the exit value. + * Whatever is printed will be sent to the Scala process standard output. If + * we wanted to caputre it, we could run that with `!!` instead. + * + * Note: though it is not shown above, the equivalent of a shell's `;` would be + * `###`. The reason for this name is that `;` is a reserved token in Scala. */ trait ProcessBuilder extends Source with Sink { - /** Starts the process represented by this builder, blocks until it exits, and returns the output as a String. Standard error is - * sent to the console. If the exit code is non-zero, an exception is thrown.*/ + /** Starts the process represented by this builder, blocks until it exits, and + * returns the output as a String. Standard error is sent to the console. If + * the exit code is non-zero, an exception is thrown. + */ def !! : String - /** Starts the process represented by this builder, blocks until it exits, and returns the output as a String. Standard error is - * sent to the provided ProcessLogger. If the exit code is non-zero, an exception is thrown.*/ + + /** Starts the process represented by this builder, blocks until it exits, and + * returns the output as a String. Standard error is sent to the provided + * ProcessLogger. If the exit code is non-zero, an exception is thrown. + */ def !!(log: ProcessLogger): String - /** Starts the process represented by this builder. The output is returned as a Stream that blocks when lines are not available - * but the process has not completed. Standard error is sent to the console. If the process exits with a non-zero value, - * the Stream will provide all lines up to termination and then throw an exception. */ + + /** Starts the process represented by this builder, blocks until it exits, and + * returns the output as a String. Standard error is sent to the console. If + * the exit code is non-zero, an exception is thrown. The newly started + * process reads from standard input of the current process. + */ + def !!< : String + + /** Starts the process represented by this builder, blocks until it exits, and + * returns the output as a String. Standard error is sent to the provided + * ProcessLogger. If the exit code is non-zero, an exception is thrown. The + * newly started process reads from standard input of the current process. + */ + def !!<(log: ProcessLogger): String + + /** Starts the process represented by this builder. The output is returned as + * a Stream that blocks when lines are not available but the process has not + * completed. Standard error is sent to the console. If the process exits + * with a non-zero value, the Stream will provide all lines up to termination + * and then throw an exception. + */ def lines: Stream[String] - /** Starts the process represented by this builder. The output is returned as a Stream that blocks when lines are not available - * but the process has not completed. Standard error is sent to the provided ProcessLogger. If the process exits with a non-zero value, - * the Stream will provide all lines up to termination but will not throw an exception. */ + + /** Starts the process represented by this builder. The output is returned as + * a Stream that blocks when lines are not available but the process has not + * completed. Standard error is sent to the provided ProcessLogger. If the + * process exits with a non-zero value, the Stream will provide all lines up + * to termination but will not throw an exception. + */ def lines(log: ProcessLogger): Stream[String] - /** Starts the process represented by this builder. The output is returned as a Stream that blocks when lines are not available - * but the process has not completed. Standard error is sent to the console. If the process exits with a non-zero value, - * the Stream will provide all lines up to termination but will not throw an exception. */ + + /** Starts the process represented by this builder. The output is returned as + * a Stream that blocks when lines are not available but the process has not + * completed. Standard error is sent to the console. If the process exits + * with a non-zero value, the Stream will provide all lines up to termination + * but will not throw an exception. + */ def lines_! : Stream[String] - /** Starts the process represented by this builder. The output is returned as a Stream that blocks when lines are not available - * but the process has not completed. Standard error is sent to the provided ProcessLogger. If the process exits with a non-zero value, - * the Stream will provide all lines up to termination but will not throw an exception. */ + + /** Starts the process represented by this builder. The output is returned as + * a Stream that blocks when lines are not available but the process has not + * completed. Standard error is sent to the provided ProcessLogger. If the + * process exits with a non-zero value, the Stream will provide all lines up + * to termination but will not throw an exception. + */ def lines_!(log: ProcessLogger): Stream[String] - /** Starts the process represented by this builder, blocks until it exits, and returns the exit code. Standard output and error are - * sent to the console.*/ + + /** Starts the process represented by this builder, blocks until it exits, and + * returns the exit code. Standard output and error are sent to the console. + */ def ! : Int - /** Starts the process represented by this builder, blocks until it exits, and returns the exit code. Standard output and error are - * sent to the given ProcessLogger.*/ + + /** Starts the process represented by this builder, blocks until it exits, and + * returns the exit code. Standard output and error are sent to the given + * ProcessLogger. + */ def !(log: ProcessLogger): Int - /** Starts the process represented by this builder, blocks until it exits, and returns the exit code. Standard output and error are - * sent to the console. The newly started process reads from standard input of the current process.*/ + + /** Starts the process represented by this builder, blocks until it exits, and + * returns the exit code. Standard output and error are sent to the console. + * The newly started process reads from standard input of the current process. + */ def !< : Int - /** Starts the process represented by this builder, blocks until it exits, and returns the exit code. Standard output and error are - * sent to the given ProcessLogger. The newly started process reads from standard input of the current process.*/ + + /** Starts the process represented by this builder, blocks until it exits, and + * returns the exit code. Standard output and error are sent to the given + * ProcessLogger. The newly started process reads from standard input of the + * current process. + */ def !<(log: ProcessLogger): Int - /** Starts the process represented by this builder. Standard output and error are sent to the console.*/ + + /** Starts the process represented by this builder. Standard output and error + * are sent to the console.*/ def run(): Process - /** Starts the process represented by this builder. Standard output and error are sent to the given ProcessLogger.*/ + + /** Starts the process represented by this builder. Standard output and error + * are sent to the given ProcessLogger. + */ def run(log: ProcessLogger): Process - /** Starts the process represented by this builder. I/O is handled by the given ProcessIO instance.*/ + + /** Starts the process represented by this builder. I/O is handled by the + * given ProcessIO instance. + */ def run(io: ProcessIO): Process - /** Starts the process represented by this builder. Standard output and error are sent to the console. - * The newly started process reads from standard input of the current process if `connectInput` is true.*/ + + /** Starts the process represented by this builder. Standard output and error + * are sent to the console. The newly started process reads from standard + * input of the current process if `connectInput` is true. + */ def run(connectInput: Boolean): Process - /** Starts the process represented by this builder, blocks until it exits, and returns the exit code. Standard output and error are - * sent to the given ProcessLogger. - * The newly started process reads from standard input of the current process if `connectInput` is true.*/ + + /** Starts the process represented by this builder, blocks until it exits, and + * returns the exit code. Standard output and error are sent to the given + * ProcessLogger. The newly started process reads from standard input of the + * current process if `connectInput` is true. + */ def run(log: ProcessLogger, connectInput: Boolean): Process - /** Constructs a command that runs this command first and then `other` if this command succeeds.*/ + /** Constructs a command that runs this command first and then `other` if this + * command succeeds. + */ def #&& (other: ProcessBuilder): ProcessBuilder - /** Constructs a command that runs this command first and then `other` if this command does not succeed.*/ + + /** Constructs a command that runs this command first and then `other` if this + * command does not succeed. + */ def #|| (other: ProcessBuilder): ProcessBuilder - /** Constructs a command that will run this command and pipes the output to `other`. `other` must be a simple command.*/ + + /** Constructs a command that will run this command and pipes the output to + * `other`. `other` must be a simple command. + */ def #| (other: ProcessBuilder): ProcessBuilder - /** Constructs a command that will run this command and then `other`. The exit code will be the exit code of `other`.*/ + + /** Constructs a command that will run this command and then `other`. The + * exit code will be the exit code of `other`. + */ def ### (other: ProcessBuilder): ProcessBuilder - /** True if this command can be the target of a pipe. - */ + + /** True if this command can be the target of a pipe. */ def canPipeTo: Boolean - /** True if this command has an exit code which should be propagated to the user. - * Given a pipe between A and B, if B.hasExitValue is true then the exit code will - * be the one from B; if it is false, the one from A. This exists to prevent output - * redirections (implemented as pipes) from masking useful process error codes. - */ + /** True if this command has an exit code which should be propagated to the + * user. Given a pipe between A and B, if B.hasExitValue is true then the + * exit code will be the one from B; if it is false, the one from A. This + * exists to prevent output redirections (implemented as pipes) from masking + * useful process error codes. + */ def hasExitValue: Boolean } |