SYNOPSIS
          arx (-h | -[?] | --help)
          arx (-v | --version)
          arx shdat (-b <size>)? (-o <output file>)? < input
          arx shdat (-b <size>)? (-o <output file>)? <input file>+
          arx tmpx <option,archive>* (//+ <command> (//+ <option,archive>*)?)?

DESCRIPTION
       A  UNIX  executable is a simple thing -- a file the kernel can execute,
       one way or another, via an interpreter  or  directly  as  object  code.
       Every  executable induces a family of executions -- instances of execu-
       tion with different command line arguments, with different files in the
       working directory and with different environment variables present.

       The  arx  tool captures the parameters of an execution and encodes them
       as an executable, making for easy, consistent transfer  and  repetition
       of  a  particular  run.  The generated executable ensures that each run
       occurs in a  freshly  allocated  temporary  directory,  with  only  the
       desired  files  in  scope;  it uses traps to ensure the cleanup of this
       directory; and its format is a simple POSIX shell  script,  relying  on
       just a few shell tools.

DEPENDENCIES
       The  arx  tool relies on the presence of sed, tr, date, head, tar, hex-
       dump and sh. When unpacking tar archives, it  may  use  the  -j  or  -z
       (bzip2 and gzip, respectively) options of tar. Scripts have been tested
       with dash and the GNU tools as well as the sh implementation and  user-
       land tools that are part of busybox.

APPLICATION
       The  tmpx  subcommand  of  arx offers a variety of options for bundling
       code and a task to run. The shdat subcommand  exposes  the  lower-level
       functionality  of  encoding  binary data in a shell script that outputs
       that binary data, using HERE documents and some odd  replacement  rules
       for nulls.

       Scripts generated by tmpx and shdat may be fed to sh over STDIN to exe-
       cute them. This can be helpful when using ssh and sudo  to  set  up  an
       execution context; for example:

          arx tmpx ... | ssh user@host.com sudo sh

       Scripts  generated  by  tmpx will pass their arguments to the contained
       script or command. To pass arguments when piping to sh, use -s:

          arx tmpx ... | ssh user@host.com sudo sh -s a b c

       Some arguments to the  generated  script  will  be  treated  specially,
       namely,  --extract,  --no-rm  and  --no-run.  Please see the section on
       Passing Arguments, below, for more information about these options.

ARX COMMANDLINE PROCESSING
       For all subcommands, when options overlap in their effect -- for  exam-
       ple,  setting  the  output with -o -- the rightmost option takes prece-
       dence.  Whenever -h, -? or --help is present on the command line,  help
       is displayed and the program exits.

       When  paths  are  specified on an arx command line, they must be quali-
       fied, starting with /, ./ or ../. This simplifies the command line syn-
       tax, overall, without introducing troublesome ambiguities.

TMPX
       The tmpx subcommand bundles together archives, environment settings and
       an executable or shell command in to a  Bourne-compatible  script  that
       runs  the  command or executable in a temporary directory, after having
       unpacked the archives and set the environment.

       Any number of file path arguments may be specified; they will be inter-
       preted  as  tar  archives  to include in bundled script. If - is given,
       then STDIN will be included as an archive stream. If no  arguments  are
       given,  it is assumed that no archives are desired and only the command
       and environment are bundled.

       The temporary directory created by the script  is  different  for  each
       invocation,  with a name of the form /tmp/tmpx-<timestamp>-<randomhex>.
       The timestamp format is %Y.%m.%dT%H.%M.%SZ, in UTC.  One  happy  conse-
       quence  of  this  is that earlier jobs sort ASCIIbetically before later
       jobs. After execution, the temporary  directory  is  removed  (or  not,
       depending on the -rm[10!_] family of options).

          -rm0, -rm1, -rm_, -rm!
                 By  default,  the  temporary  directory created by the script
                 will be deleted no matter the exit status status of the task.
                 These options cause a script to be generated that deletes the
                 temporary directory only on success, only on failure,  always
                 (the default) or never.

          --shared
                 Causes  the temporary directory to be identified by a hash of
                 the ARX archive, instead of by date and time. Different  runs
                 of  the same archive will share the same directory. Note that
                 this implies shared state and every disadvantage thereof.

          -b <size>
                 Please see the documentation for  this  option,  shared  with
                 shdat, below.

          -o <path>
                 By  default, the generated script is sent to STDOUT. With -o,
                 output is redirected to the given path.

          -e <path>
                 Causes the file specified to be packaged as the  task  to  be
                 run.  A  binary  executable, a Ruby script or a longish shell
                 script all fit here.

       In addition to these options, arguments of the form VAR=VALUE are  rec-
       ognized  as  environment  mappings and stored away in the script, to be
       sourced on execution.

       Without -e, the tmpx subcommand tries to find the task to be run  as  a
       sequence  of  arguments  delimited  by  a run of slashes. The following
       forms are all recognized:

          arx tmpx  ...some args... // ...command...
          arx tmpx  ...some args... // ...command... // ...more args...
          arx tmpx // ...command... // ...some args...

       The slash runs must have the same number of slashes  and  must  be  the
       longest  continuous  runs  of  slashes on the command line. The command
       will be included as-is in a Bourne shell script.

SHDAT
       The shdat subcommand translates binary data in to a shell script  which
       outputs  the binary data. The data is encoded in HERE documents in such
       a way that data without NULs is not changed and that data with NULs  is
       minimally  expanded:  about  1% for randomish data like compressed tar-
       balls and about 10% in pathological cases.

       The shdat subcommand can be given any number of paths,  which  will  be
       concatenated in the order given. If no path is given, or if - is given,
       then STDIN will be read.

          -b <size>
                 The size of data chunks to place in each HERE  document.  The
                 argument  is  a positive integer followed by suffixes like B,
                 K, KiB, M and MiB, in the manner of dd, head and  many  other
                 tools.  The default is 4MiB.  This is unlikely to make a dif-
                 ference for you unless the generated script is intended to be
                 run on a memory-constrained system.

          -o <path>
                 By  default, the generated script is sent to STDOUT. With -o,
                 output is redirected to the given path.

EXAMPLES
          # Installer script that preserves failed builds.
          git archive HEAD | bzip2 | arx tmpx -rm0 - // make install > go.sh
          # Now install as root; but don't log in as root.
          cat ./go.sh | ssh joey@hostname sudo /bin/sh

          # Variation of the above.
          git archive HEAD | bzip2 | arx tmpx -rm0 - -e ./build-script.py > go.sh

          # Bundle an instance of an application with DB credentials and run it.
          arx tmpx -rm! ./app.tbz ./stage-info.tgz // rake start | ssh ...

          # Get dump of linking info for build that works here but not there.
          arx tmpx ./server-build.tgz LD_DEBUG=files // ./bin/start | ssh ...

          # Test out Cabal source distribution of this package:
          arx tmpx // 'cd arx-* && cabal configure && cabal build' // \
                   -rm0 ./dist/arx-0.0.0.tar.gz | sh

PASSING ARGUMENTS TO GENERATED SCRIPTS
       The scripts generated by tmpx treat some arguments as special, internal
       options,  to allow for inspecting them should there be a need to deter-
       mine their contents.

          --extract
                 Unpack the data in the present directory and do nothing else.

          --no-rm
                 Run the script as normal but do not delete the generated tem-
                 porary directory.

          --no-run
                 Unpack into a temporary directory as normal but  do  not  run
                 the user's command.

       To  prevent arguments from being specially treated, use // in the argu-
       ment list:

          a-tmpx-script.sh --no-rm // a b c --extract

       In the above example, --extract will be passed to the inner command, in
       the same way as a, b, c. The following example causes ab, c and --no-rm
       to be printed one after another, each on their own line.

          arx tmpx // printf "'%s\n'" '"$@"' | sh -s // ab c --no-rm

NOTES
       The timestamp is not the common ISO  8601  format,  %Y-%m-%dT%H:%M:%SZ,
       because  of software and build processes that attach special meaning to
       colons in pathnames.

BUGS
       The command line parser offers no hints or help of any kind;  it  fails
       with  the simple message "argument error". The two most common mistakes
       I make are:

       o Not qualifying paths with /, ./ or ../.

       o Not specifying a subcommand (tmpx or shdat).

