A CommandLineTool process is a process implementation for executing a non-interactive application in a POSIX environment. To help accomodate of the enormous variety in syntax and semantics for input, runtime environment, invocation, and output of arbitrary programs, CommandLineTool provides the concept of "input binding" to describe how to translate input parameters to an actual program invocation, and "output binding" to describe how generate output parameters from program output.
baseCommand(character) Specifies the program to execute. If the value is an array, the first element is the program to execute, and subsequent elements are placed at the beginning of the command line in prior to any command line bindings. If the program includes a path separator character it must be an absolute path, otherwise it is an error. If the program does not include a path separator, search the $PATH variable in the runtime environment find the absolute path of the executable.
arguments[characterORCommandLineBinding] Command line bindings which are not directly associated with input parameters.
stdin[characterORExpression] A path to a file whose contents must be piped into the command's standard input stream.
stdout[characterORExpression] Capture the command's standard output stream to a file written to the designated output directory. If stdout is a string, it specifies the file name to use.If stdout is an expression, the expression is evaluated and must return a string with the file name to use to capture stdout. If the return value is not a string, or the resulting path contains illegal characters (such as the path separator /) it is an error.
successCodes[integer] Exit codes that indicate the process completed successfully.
temporaryFailCodes[integer] Exit codes that indicate the process failed due to a possibly temporary condition, where excuting the process with the same runtime environment and inputs may produce different results.
permanentFailCodes[integer] Exit codes that indicate the process failed due to a permanent logic error, where excuting the process with the same runtime environment and same inputs is expected to always fail.
The tool command line is built by applying command line bindings to the input object. Bindings are listed either as part of an input parameter using the inputBinding field, or separately using the arguments field of the CommandLineTool.
The algorithm to build the command line is as follows. In this algorithm, the sort key is a list consisting of one or more numeric and string elements. Strings are sorted lexicographically based on UTF-8 encoding.
Collect CommandLineBinding objects from arguments. Assign a sorting key [position, i] where position is CommandLineBinding.position and the i is the index in the arguments list.
Collect CommandLineBinding objects from the inputs schema and associate them with values from the input object. Where the input type is a record, array, or map, recursively walk the schema and input object, collecting nested CommandLineBinding objects and associating them with values from the input object.
Assign a sorting key for each leaf binding object by appending nested position fields together with the array index, or map key of the data at each nesting level. If two bindings have the same position, the tie must be broken using the lexographic ordering of the field or parameter name immediately containing the binding.
Sort elements using the assigned sorting keys. Numeric entries sort before strings.
In the sorted order, apply the rules defined in CommandLineBinding to convert bindings to actual command line elements.
Insert elements from baseCommand at the beginning of the command line.
All files listed in the input object must be made available in the runtime environment. The implementation may use a shared or distributed file system or transfer files via explicit download. Implementations may choose not to provide access to files not explicitly specified by the input object or process requirements.
Output files produced by tool execution must be written to the designated output directory.
The initial current working directory when executing the tool must be the designated output directory.
The TMPDIR environment variable must be set in the runtime environment to the designated temporary directory. Any files written to the designated temporary directory may be deleted by the workflow platform when the tool invocation is complete.
An implementation may forbid the tool from writing to any location in the runtime environment file system other than the designated temporary directory and designated output directory. An implementation may provide read-only input files, and disallow in-place update of input files.
The standard input stream and standard output stream may be redirected as described in the stdin and stdout fields.
DockerRequirement, CreateFileRequirement, and EnvVarRequirement, are available as standard extensions to core command line tool semantics for defining the runtime environment.
Once the command line is built and the runtime environment is created, the actual tool is executed.
The standard error stream and standard output stream (unless redirected by setting stdout) may be captured by platform logging facilities for storage and reporting.
Tools may be multithreaded or spawn child processes; however, when the parent process exits, the tool is considered finished regardless of whether any detached child processes are still running. Tools must not require any kind of console, GUI, or web based user interaction in order to start and run to completion.
The exit code of the process indicates if the process completed successfully. By convention, an exit code of zero is treated as success and non-zero exit codes are treated as failure. This may be customized by providing the fields successCodes, temporaryFailCodes, and permanentFailCodes. An implementation may choose to default unspecified non-zero exit codes to either temporaryFailure or permanentFailure.
If the output directory contains a file called "cwl.output.json", that file must be loaded and used as the output object. Otherwise, the output object must be generated by walking the parameters listed in outputs and applying output bindings to the tool output. Output bindings are associated with output parameters using the outputBinding field. See CommandOutputBinding for details.
ipl <- InputParameterList( InputParameter( id = "BAM", type = "File", label = "input bam", description = "input bam", inputBinding = CommandLineBinding( position = 1L ) ), InputParameter( id = "level", type = "Integer", label = "Compression level", description = "Compression level", inputBinding = CommandLineBinding( position = 2L, prefix = "-l" ) ) ) clt <- CommandLineTool(inputs = ipl, baseCommand = "samtools sort")