diff --git a/linuxconf b/linuxconf
index 3a9990c1e5000529a35fcb8b7792b525015e3a32..4a122fc48219ed39228e63fd02258967233dc05e 100755
--- a/linuxconf
+++ b/linuxconf
@@ -1,20 +1,20 @@
 #!/bin/bash
 
-# Useful functions as built-in
-function echo2 () {
+# Useful built-in functions for both linuxconf and user scripts.
+function lcf_echo2 () {
     echo "$@" 1>&2
 }
-function err () {
-    echo2 Error: "$@"
+function lcf_err () {
+    lcf_echo2 Error: "$@"
     return 1
 }
-function die () {
-    err "$@"
+function lcf_die () {
+    lcf_err "$@"
     exit 1
 }
-function bgrun () {
-    # Usage: bgrun /var/log/your.log sslocal -s xxx -p 'hello world my password' -l xxx --xxx
-    # Usage: bgrun /var/log/your.log auto_restart frpc -c my_server.ini
+function lcf_bgrun () {
+    # Usage: lcf_bgrun /var/log/your.log sslocal -s xxx -p 'hello world my password' -l xxx --xxx
+    # Usage: lcf_bgrun /var/log/your.log auto_restart frpc -c my_server.ini
     # v202504-1
     local logF="$1"
     shift
@@ -44,13 +44,13 @@ function lc_include () {
     # print the return code of the eval-ed function to stderr, but this function should always return success.
 
     for script in "$@"; do
-        echo2 "$script -- $LCI_SUBSHELL_OP started as $(whoami), at $(pwd)"
+        lcf_echo2 "$script -- $LCI_SUBSHELL_OP started as $(whoami), at $(pwd)"
         (
             source "$script"
             declare -F "$LCI_SUBSHELL_OP" >/dev/null 2>&1 || exit 0
             eval "$LCI_SUBSHELL_OP"
         )
-        echo2 "$script -- $LCI_SUBSHELL_OP completed with status $?"
+        lcf_echo2 "$script -- $LCI_SUBSHELL_OP completed with status $?"
         # TODO: should I abort on failure? It will stop running other include files. Don't do it now.
     done
 
@@ -81,7 +81,7 @@ function lci_fsmap () {
 function lc_fsmap () {
     lci_fsmap "$@"
     local result=$?
-    [ $result = 0 ] || err "lc_fsmap returned error $result"
+    [ $result = 0 ] || lcf_err "lc_fsmap returned error $result"
     return $result
 }
 
@@ -120,7 +120,7 @@ function lci_overwrite_conf () {
     local confpath="$2" # user masterconf script path
 
     local newpath="$(realpath "$confpath")"
-    [ "$newpath" != "" ] || err "lci_overwrite_conf: cannot unfold path $confpath. Permission error?" || return $?
+    [ "$newpath" != "" ] || lcf_err "lci_overwrite_conf: cannot unfold path $confpath. Permission error?" || return $?
 
     # Don't re-create if old config already looks good. In this case, init_done should be preserved. TODO: rename lc register to lc init, then should I remove this behavior??
     if [[ -f "$fname" ]]; then
@@ -128,26 +128,26 @@ function lci_overwrite_conf () {
         [[ "$oldpath" = "$newpath" ]] && return 0
     fi
 
-    echo -e "#autogenerated config, could be overwritten without warning.\nmasterconf=$newpath" | tee "$fname" > /dev/null || err "lci_overwrite_conf: unable to create $fname" || return $?
+    echo -e "#autogenerated config, could be overwritten without warning.\nmasterconf=$newpath" | tee "$fname" > /dev/null || lcf_err "lci_overwrite_conf: unable to create $fname" || return $?
     chmod ugo+rw "$fname"
 }
 
 
 function lci_register () {
     local confpath="$1"
-    [[ -f "$confpath" ]] || die "lci_register: $confpath not exist"
+    [[ -f "$confpath" ]] || lcf_die "lci_register: $confpath not exist"
 
     # For new register (or register a different dir), clear all existing conf. This will trigger init again.
-    lci_overwrite_conf /etc/linuxconf.conf "$confpath" || die "lci_register cannot write new conf"
+    lci_overwrite_conf /etc/linuxconf.conf "$confpath" || lcf_die "lci_register cannot write new conf"
 }
 
 function lci_call () {
     # calls an lc function in masterconf (and included subconf)
-    [ "$1" = "" ] && die "logic error: lci_call without arg"
+    [ "$1" = "" ] && lcf_die "logic error: lci_call without arg"
     export LCI_SUBSHELL_OP="$1"
-    local masterconf="$(lci_conf_get_masterconf_path /etc/linuxconf.conf)" || die "unable to call lc_init. Cannot read masterconf path from /etc/linuxconf.conf"
+    local masterconf="$(lci_conf_get_masterconf_path /etc/linuxconf.conf)" || lcf_die "unable to call lc_init. Cannot read masterconf path from /etc/linuxconf.conf"
     local workdir="$(dirname "$masterconf")"
-    cd "$workdir" || die "unable to enter config directory: $workdir"
+    cd "$workdir" || lcf_die "unable to enter config directory: $workdir"
     lc_include "$masterconf"
     export LCI_SUBSHELL_OP=__lc_operation_undefined
 }
@@ -158,7 +158,7 @@ function lci_init_if_needed () {
 
     lci_call lc_init
     
-    lci_state_file_append /etc/linuxconf.conf init_done "$uname" || die "lc_init functions succeeded, but unable to update /etc/linuxconf.conf"
+    lci_state_file_append /etc/linuxconf.conf init_done "$uname" || lcf_die "lc_init functions succeeded, but unable to update /etc/linuxconf.conf"
 }
 
 function lci_startup_if_needed () {
@@ -166,20 +166,20 @@ function lci_startup_if_needed () {
 
     local state_file="/tmp/.linuxconf-state-$uname"
     if [[ ! -f $state_file ]]; then
-        touch $state_file && chmod ugo+rw $state_file || die "failed to create tmp file $state_file"
+        touch $state_file && chmod ugo+rw $state_file || lcf_die "failed to create tmp file $state_file"
     fi
 
     lci_state_file_contains $state_file startup_done "$uname" && return 0
 
     lci_call lc_startup
    
-    lci_state_file_append $state_file startup_done "$uname" || die "lc_startup functions succeeded, but unable to update $state_file"
+    lci_state_file_append $state_file startup_done "$uname" || lcf_die "lc_startup functions succeeded, but unable to update $state_file"
 }
 
 function lci_usage () {
-    echo2 "linuxconf v$lci_version"
-    echo2 "This tool helps you manage all linux customization in one centralized directory, making backup/sync much easier."
-    echo2 "Usage: Run '$0 register <path/to/masterconf.sh>', then it will work out-of-box."
+    lcf_echo2 "linuxconf v$lci_version"
+    lcf_echo2 "This tool helps you manage all linux customization in one centralized directory, making backup/sync much easier."
+    lcf_echo2 "Usage: Run '$0 register <path/to/masterconf.sh>', then it will work out-of-box."
     exit 1
 }
 
@@ -204,14 +204,14 @@ function lci_install_startup_hook () {
         elif [ -f /etc/rc.local ]; then
             echo '/usr/bin/linuxconf _startup_all' >> /usr/bin/linuxconf _startup_all
         else
-            err "neither systemd nor /etc/rc.local available."
+            lcf_err "neither systemd nor /etc/rc.local available."
         fi || return $?
         #TODO: check if any user installed non-root startup hook
     else
         [ -f /etc/systemd/system/lc-hook.service ] && return 0
         grep '/usr/bin/linuxconf _startup_all' /etc/rc.local >/dev/null 2>&1 && return 0
         # TODO: install non-root startup hook
-        die "non-root startup hook not supported yet"
+        lcf_die "non-root startup hook not supported yet"
     fi
 }
 function lci_install_login_hook () {
@@ -245,12 +245,12 @@ function lci_install_login_hook () {
 lci_version=0.2.0
 subcommand="$1"
 if [[ "$subcommand" != register ]] && [[ "$subcommand" != "" ]]; then
-    [[ ! -f /etc/linuxconf.conf ]] && die "Please run '$0 register <path/to/masterconf.sh>' at least once"
+    [[ ! -f /etc/linuxconf.conf ]] && lcf_die "Please run '$0 register <path/to/masterconf.sh>' at least once"
 fi
 if [[ "$subcommand" = register ]]; then
     lci_register "$2"
-    lci_install_startup_hook || die "failed to install on_startup hook"
-    lci_install_login_hook || die "failed to install on_login hook"
+    lci_install_startup_hook || lcf_die "failed to install on_startup hook"
+    lci_install_login_hook || lcf_die "failed to install on_login hook"
     lci_init_if_needed
     lci_startup_if_needed
 elif [[ "$subcommand" = _cron ]]; then
@@ -260,10 +260,10 @@ elif [[ "$subcommand" = _startup ]]; then
     lci_startup_if_needed
 elif [[ "$subcommand" = _startup_all ]]; then
     # systemd should call this service as root, and it will spawn subprocess for all users with sudo
-    [[ "$(whoami)" != root ]] && die "$0 _startup_all started as non-root. Exit because sudo might fail."
-    local ar_uname=($(lci_state_file_list /etc/linuxconf.conf init_done)) || die "List all initialized users: lci_state_file_list failed"
+    [[ "$(whoami)" != root ]] && lcf_die "$0 _startup_all started as non-root. Exit because sudo might fail."
+    local ar_uname=($(lci_state_file_list /etc/linuxconf.conf init_done)) || lcf_die "List all initialized users: lci_state_file_list failed"
     for uname in "${ar_uname[@]}"; do
-        echo2 "Spawn subprocess '$0 _startup' as user $uname..."
+        lcf_echo2 "Spawn subprocess '$0 _startup' as user $uname..."
         sudo -u "$uname" "$0" _startup
     done
 elif [[ "$subcommand" = _xdg_login ]]; then