Start steam in offline mode without prompting to go online

steam-offline.sh

#!/usr/bin/env sh

# Start steam in offline mode without prompting to go online.
# https://gaming.stackexchange.com/a/184717
# NOTE: You may need to log into steam in online mode once.

# Steam resets the SkipOfflineModeWarning option on every startup.
# So we have to enable it every time before starting steam.

LOGINUSERS=~/.steam/debian-installation/config/loginusers.vdf

if [ ! -f "$LOGINUSERS" ]; then
    echo "Steam user config file not found: $LOGINUSERS"
    echo "The config must be modified to start Steam in offline mode withuot a warning."
    echo "Abort"
    exit 1
fi

# Search for a disabled option (option value 0).
# Replicate the option string by using backreference (\1).
# Set the option value to 1.
sed -i "s/\(WantsOfflineMode.*\)0/\11/" "$LOGINUSERS"
sed -i "s/\(SkipOfflineModeWarning.*\)0/\11/" "$LOGINUSERS"

steam "$@"