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Alex MillerAlex MillerLabels
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Unassigned
UnassignedReporter
Alex Miller
Alex MillerLabels
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Ok
Patch
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MajorAffects versions
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Created March 14, 2023 at 9:17 PM
Updated April 14, 2023 at 2:03 PM
Resolved April 14, 2023 at 2:03 PM
For a long time, we’ve had the clojure.java.shell api in the core library, but it does not take advantage of the newer I/O support available in the Java process API in more recent JVMs. This proposal adds a new namespace clojure.java.process with support for wrapping the Java process API and providing some conveniences for common use cases.
The primary api is
start:------------------------- clojure.java.process/start ([& opts+args]) Starts an external command as args and optional leading opts map: :in - a ProcessBuilder.Redirect (default = :pipe) or :inherit :out - a ProcessBuilder.Redirect (default = :pipe) or :inherit :discard :err - a ProcessBuilder.Redirect (default = :pipe) or :inherit :discard :stdout :dir - directory to run the command from, default="." :env - {env-var value} of environment variables (all strings) Returns an ILookup containing the java.lang.Process in :process and the streams :in :out :err. The map is also an IDeref that waits for process exit and returns the exit code.A helper is provided to make ProcessBuilder.Redirect instances that read from (for :in) or write to (for :out and :err) a stream:
------------------------- clojure.java.process/from-file ([file]) Coerce f to a file per clojure.java.io/file and return a ProcessBuilder.Redirect reading from the file. This can be passed to 'start' in :in. ------------------------- clojure.java.process/to-file ([file & {:keys [append], :as opts}]) Coerce f to a file per clojure.java.io/file and return a ProcessBuilder.Redirect writing to the file. Set ':append' in opts to append. This can be passed to 'start' in :out or :err.The return value of start is a map with keys :process :in :out :err that also can be deref’ed to wait for the process to exit. For the common case of waiting for a process to exit successfully, use
ok?:------------------------- clojure.java.process/ok? ([process-map]) Given the map returned from 'start', wait for the process to exit and then return true on successTo capture a stream to a string, use
capture:------------------------- clojure.java.process/capture ([input-stream & opts]) Read from input-stream until EOF and return a String (or nil if 0 length). Takes same opts as clojure.java.io/copy - :buffer and :encodingA useful helper covers the common case of executing a process, waiting for exit, and capturing the stdout to a string:
------------------------- clojure.java.process/exec ([& opts+args]) Execute a command and on successful exit, return the captured output, else throw RuntimeException. Args are the same as 'start' and options if supplied override the default 'exec' settings.Some examples:
(use 'clojure.java.process) ;; shell out and inherit the i/o (start {:out :inherit, :err :stdout} "ls" "-l") ;; write out and err to files, wait for process to exit, return exit code @(start {:out (to-file "out") :err (to-file "err")} "ls" "-l") ;; capture output to string (-> (start "ls" "-l") :out capture) ;; with exec (exec "ls" "-l") ;; read input from file (exec {:in (from-file "deps.edn")} "wc" "-l")Patch: clj-2759-4.patch
Pulled build compilation changes for this namespace out of the patch, will include in https://clojure.atlassian.net/browse/CLJ-2761 so the patches can apply.
Screened by: fogus