mispipe

Pipe two commands and return the exit status of the first command

$ mispipe [command1] [command2]

mispipe <command1> [command1_arguments...] <command2> [command2_arguments...]

mispipe is a specialized utility designed to create a unique bidirectional or circular piping mechanism between two commands. Unlike standard Unix pipes (|) which connect the standard output of one command to the standard input of another in a linear fashion, mispipe enables a feedback loop. It typically works by taking the standard output of the first command and feeding it as standard input to the second command, and simultaneously, taking the standard output of the second command and feeding it back as standard input to the first command.

This allows for complex interactions where both commands can process data from each other in a continuous loop. It's particularly useful for scenarios where a command's output needs to influence its own subsequent input, or when two processes need to exchange data in a mutually dependent way. Due to its non-standard nature, mispipe is often implemented as a custom shell script using constructs like named pipes (mkfifo), temporary files, or process substitution, rather than being a universally installed binary. Its exact behavior and options can vary depending on its specific implementation.

Non-Standard Utility: mispipe is not a standard, universally installed Linux utility. It is often a custom shell script or a specialized tool created for specific environments. Therefore, its availability, exact syntax, behavior, and underlying implementation (e.g., using named pipes, temporary files, or process substitution) can vary significantly. Users should be aware that mispipe may not be present on all systems or may behave differently than expected based on its local implementation.

Resource Consumption: Circular piping can lead to complex interactions and potential resource consumption issues (e.g., CPU, memory, disk I/O for temporary files) if the commands involved do not properly handle input/output termination or produce an excessive amount of data in a continuous loop. Careful design of the piped commands is essential to prevent infinite loops or resource exhaustion.

Because mispipe is not a standard command, it's typically implemented using various shell scripting techniques. Common methods include:
Named Pipes (mkfifo): Creating two named pipes, one for each direction of the data flow, and running the commands in the background, redirecting their I/O through these pipes.
Temporary Files: Less efficient but simpler for some scenarios, where output is written to a temporary file, and that file is then read as input. This requires careful management of file deletion.
Process Substitution (<()>): In modern shells like Bash, process substitution can sometimes be used to create pseudo-files that represent the output/input of another process, enabling more complex data flow orchestration without explicit named pipes.

As mispipe is not a standard Unix command but rather a conceptual utility or a common term for a specific type of shell scripting pattern, it does not have a formal development history or a specific versioning roadmap like standard GNU utilities. Its origins lie in the need to solve complex inter-process communication problems where linear pipes are insufficient. Implementations have evolved with shell capabilities, leveraging features like named pipes (mkfifo) from the early days of Unix and later process substitution (<()>) in modern shells (like Bash and Zsh) to provide more elegant and efficient solutions for circular data flow.

mkfifo(1), xargs(1), pipe(7)