Re: New utility suggestion: chdir(1)

[Colin Watson]

Incidentally, here's a simplified excerpt of Python code from a project
I maintain at my day job (https://launchpad.net/launchpad-buildd) which
could benefit from this, and also illustrates chaining the similar
env(1) as well:


import re
import subprocess


non_meta_re = re.compile(r'^[a-zA-Z0-9+,./:=@_-]+$')

def shell_escape(arg):
    if non_meta_re.match(arg):
        return arg
    else:
        return "'%s'" % arg.replace("'", "'\\''")

def run_build_command(chroot_path, args, env=None):
    """Run a build command in the chroot.

    This is unpleasant because we need to run it in /build under sudo
    chroot, and there's no way to do this without either a helper
    program in the chroot or unpleasant quoting.  We go for the
    unpleasant quoting.
    """
    args = [shell_escape(arg) for arg in args]
    if env:
        args = (
            ["env"] +
            ["%s=%s" % (key, shell_escape(value))
             for key, value in env.items()] +
            args)
    command = "cd /build && %s" % " ".join(args)
    subprocess.check_call(
        ["sudo", "chroot", chroot_path, "/bin/sh", "-c", command])


With chdir(1), this would become something like:


def run_build_command(chroot_path, args, env=None):
    """Run a build command in the chroot."""
    if env:
        args = (
            ["env"] +
            ["%s=%s" % (key, value) for key, value in env.items()] +
            args)
    subprocess.check_call(
        ["sudo", "chroot", chroot_path, "chdir", "/build"] + args)

-- 
Colin Watson                                       [address@hidden]