curl installer.sh --install-mode [global|user]

global mode: env self (epkg manager): shared /opt/epkg/store: shared

env: per-user

global mode install actions: epkg manager's env -> global set uid epkg root-helper binary

design:

HOME_EPKG=$HOME/.epkg
OPT_EPKG=/opt/epkg
PUB_EPKG=$OPT_EPKG/users/public

if EPKG_INSTALL_MODE==global and EPKG_ENV_NAME==self:
    EPKG_USER_DIR=$HOME_EPKG
else:
    EPKG_USER_DIR=$PUB_EPKG

EPKG_SELF_ENV_ROOT: self env根目录
	global | user: $PUB_EPKG/envs
EPKG_ENV_ROOT:
	global | user: $EPKG_USER_DIR/envs
EPKG_CONFIG_DIR:
	global | user: $EPKG_USER_DIR/config
EPKG_TEMP:
	global | user: $EPKG_USER_DIR/tmp
EPKG_STORE_ROOT:
	global: $OPT_EPKG/store
	user:   $HOME_EPKG/store
EPKG_CACHE:
	global: $OPT_EPKG/cache
	user:   $HOME/.cache/epkg
EPKG_PKG_CACHE_DIR:
	global | user: $EPKG_CACHE/packages
EPKG_CHANNEL_CACHE_DIR:
	global | user: $EPKG_CACHE/channel
EPKG_INIT_ROOT:
	global: /opt/.epkg/.init
	user:   $HOME_EPKG/.init

epkg-helper(root-helper)

epkg-helper: Operate the /opt/.epkg directory
- EPKG_COMM_ENV_ROOT: /opt/.epkg/envs/
- EPKG_PKG_CACHE_DIR: /opt/.cache/epkg/packages
- EPKG_CHANNEL_CACHE_DIR: /opt/.cache/epkg/channel
- EPKG_STORE_ROOT: /opt/.epkg/store
- EPKG_TEMP: /opt/.temp
Add SUID permission to epkg-helper, and close other permissions for the /opt/.epkg/store directory
- chown root:root /usr/bin/epkg_helper
- chmod 4755 /usr/bin/epkg_helper
- chmod 755 /opt/.epkg/
Keep the external interface unchanged, e.g., epkg install tree
- Global mode: epkg calls epkg-helper to operate the comm & store directory
- User mode: The store directory is located in $HOME, no need to use epkg-helper