@hackage arx0.3.2

SYNOPSIS arx (-h | -[?] | --help) arx (-v | --version) arx shdat (-b )? (-o

)? < input arx shdat (-b )? (-o

)? + arx tmpx <option,archive>* (//+ (//+ <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).