Plumbum: Shell Combinators
Ever wished the compactness of shell scripts be put into a real programming language? Say hello to Plumbum Shell Combinators. Plumbum (Latin for lead, which was used to create pipes back in the day) is a small yet feature-rich library for shell script-like programs in Python. The motto of the library is "Never write shell scripts again", and thus it attempts to mimic the shell syntax ("shell combinators") where it makes sense, while keeping it all Pythonic and cross-platform.
Apart from shell-like syntax and handy shortcuts, the library provides local and remote command execution (over SSH), local and remote file-system paths, easy working-directory and environment manipulation, and a programmatic Command-Line Interface (CLI) application toolkit. Now let's see some code!
This is only a teaser; the full documentation can be found at Read the Docs
>>> from plumbum import local >>> ls = local["ls"] >>> ls LocalCommand(<LocalPath /bin/ls>) >>> ls() u'build.py\ndist\ndocs\nLICENSE\nplumbum\nREADME.rst\nsetup.py\ntests\ntodo.txt\n' >>> notepad = local["c:\\windows\\notepad.exe"] >>> notepad() # Notepad window pops up u'' # Notepad window is closed by user, command returns
Instead of writing xxx = local["xxx"] for every program you wish to use, you can also import commands:
>>> from plumbum.cmd import grep, wc, cat, head >>> grep LocalCommand(<LocalPath /bin/grep>)
>>> chain = ls["-a"] | grep["-v", "\\.py"] | wc["-l"] >>> print chain /bin/ls -a | /bin/grep -v '\.py' | /usr/bin/wc -l >>> chain() u'13\n'
>>> ((cat < "setup.py") | head["-n", 4])() u'#!/usr/bin/env python\nimport os\n\ntry:\n' >>> (ls["-a"] > "file.list")() u'' >>> (cat["file.list"] | wc["-l"])() u'17\n'
>>> local.cwd <Workdir /home/tomer/workspace/plumbum> >>> with local.cwd(local.cwd / "docs"): ... chain() ... u'15\n'
Foreground and background execution
>>> from plumbum import FG, BG >>> (ls["-a"] | grep["\\.py"]) & FG # The output is printed to stdout directly build.py .pydevproject setup.py >>> (ls["-a"] | grep["\\.py"]) & BG # The process runs "in the background" <Future ['/bin/grep', '\\.py'] (running)>
>>> from plumbum.cmd import sudo >>> print sudo[ifconfig["-a"]] /usr/bin/sudo /sbin/ifconfig -a >>> (sudo[ifconfig["-a"]] | grep["-i", "loop"]) & FG lo Link encap:Local Loopback UP LOOPBACK RUNNING MTU:16436 Metric:1
Remote commands (over SSH)
>>> from plumbum import SshMachine >>> remote = SshMachine("somehost", user = "john", keyfile = "/path/to/idrsa") >>> r_ls = remote["ls"] >>> with remote.cwd("/lib"): ... (r_ls | grep["0.so.0"])() ... u'libusb-1.0.so.0\nlibusb-1.0.so.0.0.0\n'
import logging from plumbum import cli class MyCompiler(cli.Application): verbose = cli.Flag(["-v", "--verbose"], help = "Enable verbose mode") include_dirs = cli.SwitchAttr("-I", list = True, help = "Specify include directories") @cli.switch("--loglevel", int) def set_log_level(self, level): """Sets the log-level of the logger""" logging.root.setLevel(level) def main(self, *srcfiles): print "Verbose:", self.verbose print "Include dirs:", self.include_dirs print "Compiling:", srcfiles if __name__ == "__main__": MyCompiler.run()
$ python simple_cli.py -v -I foo/bar -Ispam/eggs x.cpp y.cpp z.cpp Verbose: True Include dirs: ['foo/bar', 'spam/eggs'] Compiling: ('x.cpp', 'y.cpp', 'z.cpp')