steamcmd
A command-line version of the Steam client. tldr-pages
On several platforms
Several platforms
Install or update an application anonymously
steamcmd +login anonymous +app_update app_id +quitIdentifyInstall or update an application using the specified credentials
steamcmd +login username +app_update app_id +quitIdentifyDefine a custom install location
steamcmd +force_install_dir path/to/directory +login anonymous +app_update app_id validate +quitIdentifyInstall an application for a specific platform
steamcmd +@sSteamCmdForcePlatformType windows +login anonymous +app_update app_id validate +quitIdentifyRun a script file
steamcmd +runscript script.txtIdentifyClear cached login credentials for a user
steamcmd +login username +logout +quitIdentify