Your system information

• Steam client version (build number or date): Dec 25, '18
• Distribution (e.g. Ubuntu): debian stretch
• Opted into Steam client beta?: [Yes/No] No
• Have you checked for system updates?: [Yes/No] N/A

Please describe your issue in as much detail as possible:

Describe what you expected should happen and what did happen. Please link any large code pastes as a Github Gist

After starting steam, steam used sudo to install some additional dependencies and tried to start. It core dumped before any UI was shown.

Steps for reproducing this issue:

$ wget https://steamcdn-a.akamaihd.net/client/installer/steam.deb &&\
    (dpkg -i steam.deb || apt-get -yf install) && dpkg -i steam.deb

user@2e7708e58948:~$ steam # then provide sudo password for install
Running Steam on debian 9 64-bit
STEAM_RUNTIME is enabled automatically
Pins up-to-date!
Installing breakpad exception handler for appid(steam)/version(1543346820)
Installing breakpad exception handler for appid(steam)/version(1543346820)
Installing breakpad exception handler for appid(steam)/version(1543346820)
sh: 1: lspci: not found
Installing breakpad exception handler for appid(steam)/version(1543346820)
Fontconfig error: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 70: non-double matrix element
Fontconfig error: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 70: non-double matrix element
Fontconfig warning: "/etc/fonts/conf.d/10-scale-bitmap-fonts.conf", line 78: saw unknown, expected number
[1225/124325.686748:INFO:crash_reporting.cc(216)] Crash reporting enabled for process: browser
Installing breakpad exception handler for appid(steam)/version(1543346820)
Installing breakpad exception handler for appid(steam)/version(1543346820)
Installing breakpad exception handler for appid(steam)/version(1543346820)
[1225/124325.708982:WARNING:crash_reporting.cc(255)] Failed to set crash key: UserID with value: 0
[1225/124325.709252:WARNING:crash_reporting.cc(255)] Failed to set crash key: BuildID with value: 1543263366
[1225/124325.709281:WARNING:crash_reporting.cc(255)] Failed to set crash key: SteamUniverse with value: Public
[1225/124325.709301:WARNING:crash_reporting.cc(255)] Failed to set crash key: Vendor with value: Valve
[1225/124325.721851:ERROR:gpu_process_transport_factory.cc(1026)] Lost UI shared context.
Installing breakpad exception handler for appid(steam)/version(1543346820)
Installing breakpad exception handler for appid(steam)/version(1543346820)
CApplicationManagerPopulateThread took 0 milliseconds to initialize (will have waited on CAppInfoCacheReadFromDiskThread)
Installing breakpad exception handler for appid(steam)/version(1543346820)
CAppInfoCacheReadFromDiskThread took 33 milliseconds to initialize
Installing breakpad exception handler for appid(steam)/version(1543346820)
Installing breakpad exception handler for appid(steam)/version(1543346820)
Installing breakpad exception handler for appid(steam)/version(1543346820)
Installing breakpad exception handler for appid(steam)/version(1543346820)
Installing breakpad exception handler for appid(steam)/version(1543346820)
Installing breakpad exception handler for appid(steam)/version(1543346820)
Installing breakpad exception handler for appid(steam)/version(1543346820)
Installing breakpad exception handler for appid(steam)/version(1543346820)
Installing breakpad exception handler for appid(steam)/version(1543346820)
assert_20181225124322_1.dmp[1296]: Uploading dump (out-of-process)
/tmp/dumps/assert_20181225124322_1.dmp
/home/user/.local/share/Steam/steam.sh: line 889:  1239 Segmentation fault      (core dumped) $STEAM_DEBUGGER "$STEAMROOT/$STEAMEXEPATH" "$@"
assert_20181225124322_1.dmp[1296]: Finished uploading minidump (out-of-process): success = yes
assert_20181225124322_1.dmp[1296]: response: CrashID=bp-3f2800ee-6395-4fa1-a4d4-f9c6b2181225
assert_20181225124322_1.dmp[1296]: file ''/tmp/dumps/assert_20181225124322_1.dmp'', upload yes: ''CrashID=bp-3f2800ee-6395-4fa1-a4d4-f9c6b2181225''