Skip to content

Sys.timezone() fails on Linux under Microsoft WSL

4 messages · Brenton Wiernik, Martin Maechler, Jim Hester

Brenton Wiernik
# 
In Microsoft?s Windows Subsystem for Linux (WSL or WSL2), there is not system framework, so utilities that depend on it fail. This includes timedatectl which R uses in Sys.timezone(). The timedatectl utility is present on Linux systems installed under WSL/WSL2, but is non-functional. So, when Sys.timezone() checks for Sys.which("timedatectl"), it receives a false positive. The subsequent methods after this if () do work, however.

This can be fixed if line 42 of Sys.timezone() were changed from:
if (nzchar(Sys.which("timedatectl"))) {

to:
if (nzchar(Sys.which("timedatectl")) && !grepl("microsoft", system("uname -r", intern = TRUE), ignore.case = TRUE)) {

"uname -r" returns for example:
"5.4.72-microsoft-standard-WSL2"

So checking for "microsoft" or "WSL" would probably work.


Brenton Wiernik
Martin Maechler
# 
> In Microsoft?s Windows Subsystem for Linux (WSL or WSL2),
    > there is not system framework, so utilities that depend on
    > it fail. This includes timedatectl which R uses in
    > Sys.timezone(). The timedatectl utility is present on
    > Linux systems installed under WSL/WSL2, but is
    > non-functional. So, when Sys.timezone() checks for
    > Sys.which("timedatectl"), it receives a false
    > positive. The subsequent methods after this if () do work,
    > however.

    > This can be fixed if line 42 of Sys.timezone() were changed from:

    > if (nzchar(Sys.which("timedatectl"))) {

    > to:

    > if (nzchar(Sys.which("timedatectl")) && !grepl("microsoft", system("uname -r", intern = TRUE), ignore.case = TRUE)) {

    > "uname -r" returns for example:  "5.4.72-microsoft-standard-WSL2"

    > So checking for "microsoft" or "WSL" would probably work.

    > Brenton Wiernik

Thank you.  This all makes sense.
However,  using system("uname -r")  creates another platform
dependency (it fails, i.e., signals an error, e.g., on our Windows Server).

Could  Sys.info()  be used instead?
What does it give on your platform?



    > [[alternative HTML version deleted]]

    > ______________________________________________
    > R-devel at r-project.org mailing list
    > https://stat.ethz.ch/mailman/listinfo/r-devel
Brenton Wiernik
# 
That would work.

Sys.info()['release']
#                          release 
# "5.4.72-microsoft-standard-WSL2"

Brenton


From: Martin Maechler
Sent: Wednesday, April 14, 2021 03:28
To: Brenton Wiernik
Cc: r-devel at r-project.org
Subject: Re: [Rd] Sys.timezone() fails on Linux under Microsoft WSL
> In Microsoft?s Windows Subsystem for Linux (WSL or WSL2),
    > there is not system framework, so utilities that depend on
    > it fail. This includes timedatectl which R uses in
    > Sys.timezone(). The timedatectl utility is present on
    > Linux systems installed under WSL/WSL2, but is
    > non-functional. So, when Sys.timezone() checks for
    > Sys.which("timedatectl"), it receives a false
    > positive. The subsequent methods after this if () do work,
    > however.

    > This can be fixed if line 42 of Sys.timezone() were changed from:

    > if (nzchar(Sys.which("timedatectl"))) {

    > to:

    > if (nzchar(Sys.which("timedatectl")) && !grepl("microsoft", system("uname -r", intern = TRUE), ignore.case = TRUE)) {

    > "uname -r" returns for example:  "5.4.72-microsoft-standard-WSL2"

    > So checking for "microsoft" or "WSL" would probably work.

    > Brenton Wiernik

Thank you.  This all makes sense.
However,  using system("uname -r")  creates another platform
dependency (it fails, i.e., signals an error, e.g., on our Windows Server).

Could  Sys.info()  be used instead?
What does it give on your platform?



    > [[alternative HTML version deleted]]

    > ______________________________________________
    > R-devel at r-project.org mailing list
    > https://stat.ethz.ch/mailman/listinfo/r-devel
12 days later
Jim Hester
# 
One way to avoid the call to timedatectl is to set the `TZ` environment
variable on your machine to your local timezone, if this is set
`Sys.timezone()` uses this and does not try to query timedatectl for the
timezone.

This is a common issue as well in docker containers, as like on WSL in
docker timedatectl is present, but non-functional.

Jim
On Tue, Apr 13, 2021 at 9:19 AM Brenton Wiernik <brenton at wiernik.org> wrote: