;This is the syntax I have used

ncl 0> fils = (/"pr_day_CMCC-CM_rcp85_r1i1p1_20060101-20061231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20070101-20071231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20080101-20081231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20090101-20091231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20100101-20101231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20110101-20111231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20120101-20121231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20130101-20131231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20140101-20141231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20150101-20151231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20160101-20161231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20170101-20171231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20180101-20181231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20190101-20191231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20200101-20201231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20210101-20211231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20220101-20221231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20230101-20231231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20240101-20241231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20250101-20251231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20260101-20261231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20270101-20271231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20280101-20281231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20290101-20291231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20300101-20301231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20310101-20311231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20320101-20321231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20330101-20331231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20340101-20341231.nc","pr_day_CMCC-CM_rcp85_r1i1p1_20350101-20351231.nc"/)
ncl 1> f=addfiles(fils,"r")
ncl 2> ListSetType(f,"cat")
ncl 3> pr=f[:]->pr
ncl 4> ncdf=addfile("pr_day_CMCC-CM_rcp85_r1i1p1_20060101-20351231.nc","c")
ncl 5> filedimdef(ncdf,"time",-1,True)
ncl 6> ncdf->pr=pr
fatal:File too large: error attempting to write variable (pr) to file (pr_day_CMCC-CM_rcp85_r1i1p1_20060101-20351231.nc)
fatal:["Execute.c":8573]:Execute: Error occurred at or near line 6



; I am getting same error with these syntax as well

fils = systemfunc("ls *.nc")
f = addfiles(fils,"r")
ListSetType(f,"cat")
pr=f[:]->pr
ncdf=addfile("pr_day_CMCC-CM_rcp85_r1i1p1_20060101-20351231.nc","c")
filedimdef(ncdf,"time",-1,True)
ncdf->pr=pr



*********************************************************************************

; Summary of one file

ncl 0> a=addfile("pr_day_CMCC-CM_rcp85_r1i1p1_20060101-20061231.nc","r")
ncl 1> printVarSummary(a)

Variable: a
Type: file
File path:	pr_day_CMCC-CM_rcp85_r1i1p1_20060101-20061231.nc
Number of global attributes:	 28
Number of dimensions:	 4
Number of variables:	 7


ncl 2> b=a->pr
ncl 3> printVarSummary(b)

Variable: b
Type: float
Total Size: 168192000 bytes
            42048000 values
Number of Dimensions: 3
Dimensions and sizes:	[time | 365] x [lat | 240] x [lon | 480]
Coordinates: 
            time: [ 0.5..364.5]
            lat: [-89.42708417603751..89.42708417603751]
            lon: [   0..359.25]
Number Of Attributes: 11
  standard_name :	precipitation_flux
  long_name :	Precipitation
  comment :	at surface; includes both liquid and solid phases from all types of clouds (both large-scale and convective)
  units :	kg m-2 s-1
  original_name :	precip
  cell_methods :	time: mean (interval: 1 day)
  cell_measures :	area: areacella
  missing_value :	1e+20
  _FillValue :	1e+20
  associated_files :	baseURL: http://cmip-pcmdi.llnl.gov/CMIP5/dataLocation gridspecFile: gridspec_atmos_fx_CMCC-CM_rcp85_r0i0p0.nc areacella: areacella_fx_CMCC-CM_rcp85_r0i0p0.nc
  history :	2012-02-15T12:41:27Z altered by CMOR: Inverted axis: lat.