Perl warning Setting locale failed in Debian

When installing Debian or Ubuntu, the locales may not be completely set. During the installation of Perl applications (such as Nagios), the warning, perl: warning: Setting locale failed, may be displayed.

Warning Message

The warning message during the installation of Perl applications will appear as follows:

perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
	LANGUAGE = (unset),
	LC_ALL = (unset),
	LANG = "en_US.utf8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").

This problem may arise when packages are being added. The following example will show a corresponding output:

8000050000:~# apt-get install multipath-tools
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following extra packages will be installed:
  dmsetup kpartx libaio1
Suggested packages:
  multipath-tools-boot
The following NEW packages will be installed:
  dmsetup kpartx libaio1 multipath-tools
0 upgraded, 4 newly installed, 0 to remove and 0 not upgraded.
Need to get 266kB of archives.
After this operation, 950kB of additional disk space will be used.
Do you want to continue [Y/n]? y
Get:1 http://ftp.de.debian.org lenny/main dmsetup 2:1.02.27-4 [39.7kB]
Get:2 http://ftp.de.debian.org lenny/main kpartx 0.4.8-14+lenny2 [26.0kB]
Get:3 http://ftp.de.debian.org lenny/main libaio1 0.3.107-3 [7414B]
Get:4 http://ftp.de.debian.org lenny/main multipath-tools 0.4.8-14+lenny2 [193kB]
Fetched 266kB in 1s (154kB/s)           
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
	LANGUAGE = (unset),
	LC_ALL = (unset),
	LANG = "en_US.utf8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or directory
locale: Cannot set LC_ALL to default locale: No such file or directory
Selecting previously deselected package dmsetup.
(Reading database ... 27499 files and directories currently installed.)
Unpacking dmsetup (from .../dmsetup_2%3a1.02.27-4_amd64.deb) ...
Selecting previously deselected package kpartx.
Unpacking kpartx (from .../kpartx_0.4.8-14+lenny2_amd64.deb) ...
Selecting previously deselected package libaio1.
Unpacking libaio1 (from .../libaio1_0.3.107-3_amd64.deb) ...
Selecting previously deselected package multipath-tools.
Unpacking multipath-tools (from .../multipath-tools_0.4.8-14+lenny2_amd64.deb) ...
Processing triggers for man-db ...
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
	LANGUAGE = (unset),
	LC_ALL = (unset),
	LANG = "en_US.utf8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
/usr/bin/mandb: can't set the locale; make sure $LC_* and $LANG are correct
manconv: can't set the locale; make sure $LC_* and $LANG are correct
manconv: can't set the locale; make sure $LC_* and $LANG are correct
manconv: can't set the locale; make sure $LC_* and $LANG are correct
manconv: can't set the locale; make sure $LC_* and $LANG are correct
manconv: can't set the locale; make sure $LC_* and $LANG are correct
manconv: can't set the locale; make sure $LC_* and $LANG are correct
manconv: can't set the locale; make sure $LC_* and $LANG are correct
manconv: can't set the locale; make sure $LC_* and $LANG are correct
manconv: can't set the locale; make sure $LC_* and $LANG are correct
manconv: can't set the locale; make sure $LC_* and $LANG are correct
manconv: can't set the locale; make sure $LC_* and $LANG are correct
Setting up dmsetup (2:1.02.27-4) ...
Setting up kpartx (0.4.8-14+lenny2) ...
Setting up libaio1 (0.3.107-3) ...
Setting up multipath-tools (0.4.8-14+lenny2) ...
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
	LANGUAGE = (unset),
	LC_ALL = (unset),
	LANG = "en_US.utf8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
Starting multipath daemon: multipathd.
perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
	LANGUAGE = (unset),
	LC_ALL = (unset),
	LANG = "en_US.utf8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
8000050000:~# 

Generating locales

Missing locales are generated with locale-gen:

locale-gen en_US.UTF-8

Alternatively a locale file can be created manually with localedef:

localedef -i en_US -f UTF-8 en_US.UTF-8

Setting Locale Settings

The locale settings can be set (to en_US.UTF-8 in the example) as follows:

export LANGUAGE=en_US.UTF-8
export LANG=en_US.UTF-8
export LC_ALL=en_US.UTF-8
locale-gen en_US.UTF-8
dpkg-reconfigure locales

The dpkg-reconfigure locales command will open a dialog under Debian for selecting the desired locale. This dialog will not appear under Ubuntu. The Configure Locales in Ubuntu article shows how to find the information regarding Ubuntu.

References

Author: Werner Fischer Werner Fischer, working in the Knowledge Transfer team at Thomas-Krenn, completed his studies of Computer and Media Security at FH Hagenberg in Austria. He is a regular speaker at many conferences like LinuxTag, OSMC, OSDC, LinuxCon, and author for various IT magazines. In his spare time he enjoys playing the piano and training for a good result at the annual Linz marathon relay.