Added modiciation from a parallel project

_home/dot_sz.shrc.d/02_shlvl

@@ -0,0 +1,23 @@
+function shlvl() {
+    local SHLVL_VAR="SHLVL_${SFP##*.}"
+    local SHELLS=$( \
+        cat /etc/shells \
+            | tail +2 \
+            | sed 's/.*\///' \
+            | sort -u \
+            | grep -v tmux \
+            | paste -sd '|' \
+    )
+    local SHLVL_VAL=$(eval "printf '%s' \"\$$SHLVL_VAR\"")
+    if [[ -z "$SHLVL_VAL" ]]; then
+        SHLVL_VAL=$(( $( \
+            pstree -s $$ \
+            | head -1 \
+            | sed -r 's/-\+-/---/g; s/-[^-]+---oh-my-posh---.*/-/; s/---/\n/g;' \
+            | grep -Ec "^($SHELLS)$" 
+        ) - ${1:-1} ))
+        eval "export $SHLVL_VAR=$SHLVL_VAL" 
+    fi
+    echo $SHLVL_VAL
+}
+shlvl > /dev/null