merge.bash

#!/bin/bash
OutFileName="X.csv"                       # Fix the output name
i=0                                       # Reset a counter
for filename in ./csv/*.csv; do
 if [ "$filename"  != "$OutName" ] ;      # Avoid recursion
 then
   if [[ $i -eq 0 ]] ; then
      head -1  $filename >   $OutFileName # Copy header if it is the first file
   fi
   tail -n +2  $filename >>  $OutFileName # Append from the 2nd line each file
   i=$(( $i + 1 ))                        # Increase the counter
 fi
done