The Object Pipeline
Apress eBooks · 2008
The primary use for a shell is to run commands. The shell interprets user input and launches one or more commands according to that. A user who wants to specify a complex action to perform has to invoke the right commands in the right order with the right data. Because creating a complex command that does many things and is flexible enough to meet everyone’s needs is difficult, most shells move away from monolithic do-it-all commands and instead concentrate on providing small tools that can combine their power into something big. Each of those tools usually does one specific job extremely well. For example, a hypothetical command that searches through all files with the .txt extension in a project folder and displays all occurrences of the “financial report” phrase is hard to make very flexible. What if we want to search in files modified last week? It is much easier to create two commands: Find-File to finds files according to criteria such as file extension, modification date, and so on and Search-Contents to search for words or phrases inside files. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.