Not sure if this can be done without macros, maybe someone else could give alternate answer.
To use a macro, from windows , but hopefully similar in Linux:-
"C:\Program Files\LibreOffice 5\program\soffice" --headless "Untitled 3.xls" "macro:///Standard.Module10.WriteCsvSheets()"
This will run the following basic macro from Standard Module10 in My Macros.
REM ***** BASIC *****
Option Explicit
Sub WriteCsvSheets()
Dim oDoc As Object
Dim oSheet As Object
Dim Args(1) As New com.sun.star.beans.PropertyValue
Dim sDirectory As String
Dim sFileName As String
oDoc = thisComponent
sFileName = oDoc.Title
sDirectory = replace(oDoc.Location, "%20", " " ) ' Allow for spaces in name as %20
sDirectory = replace(sDirectory, sFileName, "" )
sFileName = left(sFileName, instr(sFileName,".") - 1)
For Each oSheet in oDoc.Sheets
' Make the sheet active
oDoc.getcurrentController.setActiveSheet(oSheet)
' msgbox "test calling macro from command line" & chr(10) & oSheet.name ' Debug only
Args(0).Name = "FilterName"
Args(0).Value = "Text - txt - csv (StarCalc)"
Args(1).Name = "Overwrite"
Args(1).value = false
On Error Resume Next
oDoc.storeAsURL( sDirectory & sFileName & "_" & oSheet.name & ".csv", Args)
On Error Goto 0
Next oSheet
thisComponent.Close(true)
End Sub