[systemd-devel] [Feature request] A way to native import /proc/cmdline within unit

Lennart Poettering lennart at poettering.net
Mon Jul 29 16:12:39 PDT 2013

On Thu, 25.07.13 19:35, Gerardo Exequiel Pozzi (vmlinuz386 at yahoo.com.ar) wrote:

> On 07/25/2013 05:06 PM, Lennart Poettering wrote:
> > On Sat, 20.07.13 16:37, Gerardo Exequiel Pozzi (vmlinuz386 at yahoo.com.ar) wrote:
> > 
> >> Hello
> >>
> >> I am maintainer of Archiso project (The Arch Linux live ISO creator).
> >>
> >> I like a feature for systemd within unit files, mainly for importing
> >> /proc/cmdline in initramfs stage, or in a generic form for any other
> >> file with a similar format. Something like ImportOneLineFile=, like
> >> current EnvironmentFile=.
> >>
> >> In this way, we can use/pass parameters to Exec*= directives if needed.
> > 
> > So you awant to import kernel cmdline arguments into your environment?
> Yes, in a particular unit.
> > Note that you can do that already with the systemd.setenv= kernel
> > command line option. What else do you need?
> > 
> Yes. But doing in this way:
> * Makes each variable passed, global to all units.
> * For each parameter that I need to process I need to prefix them.
> So for example
> archisobasedir=arch archisolabel=ARCH_201307 checksum=y
> becomes:
> systemd.setenv=archisobasedir=arch
> systemd.setenv=archisolabel=ARCH_201307 systemd.setenv=checksum=y
> And if booting via PXE, think about automatic cmdline appended by
> The other solution that I have is using a service+script for
> parsing/dumping cmdline in a file, then import with EnvironmentFile= but
> does not look good. Other way maybe is using a generator, but they run
> too early and I need to wait for some things happens before generating
> units in a dynamic way.

Hmm, but how do you process those variables further? In a shell script
anyway? That sounds as if it would be appropriate to also parse
/proc/cmdline from there? Why would it be better to do this in systemd
rather than in the shell script itself?

(or similar: better than in the Pythons script itself, Perl script, C
program ...)


Lennart Poettering - Red Hat, Inc.

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