NAME

       ncoffsets - print the starting/ending file offsets for netCDF variables

SYNOPSIS

       ncoffsets [-h] | [-x] | [-sgr] [-v var1[,...]]  file

DESCRIPTION

       ncoffsets  prints  the  file  offsets information of variables defined in a given netCDF file. The ending
       offsets reported is an exclusive offset, i.e.  1 byte more than the last byte occupied by  the  variable.
       In  other  words,  the  ending  offset is equal to the sum of starting offset and the variable size.  For
       record variables, only the offsets of first record are printed. Add option -r to print the offsets of all
       records.

       If no argument is given, command usage information is printed.

OPTIONS

       -v var1[,...]
              The output will only display the offset information for the specified variables. Names of  one  or
              more variables must be provided in the comma-delimited list which must not contain blanks or other
              white  space characters. The named variables must be valid netCDF variables in the input file. The
              default, i.e., without this option, is to display the offset information for all variables  stored
              in the input file.

       -s     Print the variable size in bytes. For record variables, only the size of one record is printed.

       -g     Print  the  gap in bytes from the previous variable. For the first defined variable, print the gap
              from the end of file header. For record variables, there is no gap between records.

       -r     Output the offset information for all records of the selected record variables.  Without this  op‐
              tion, only the offsets of first record are printed.

       -x     Check  all  fixed-size  variable for file space gaps in between any two immediately adjacent vari‐
              ables. It prints "1" on stdout if gaps are found, "0" for otherwise. This option disables all oth‐
              er options.

       -h     Print the available command-line options

EXAMPLES

       Print the file offset information for all variables in a netCDF file.

       % ncoffsets -sg testfile.nc
       netcdf testfile.nc {
       // File format: CDF-1
       // Number of dimensions: 4
       // Number of variables: 4
       // Number of global attributes: 0

       file header:
           size   = 256 bytes
           extent = 512 bytes

       dimensions:
           time = UNLIMITED // (101 currently)
           Z = 100
           Y = 100
           X = 100

       fixed-size variables:
           float  square(Y, X):
                  start file offset =         512
                  end   file offset =       40512
                  size in bytes     =       40000
                  gap from prev var =         256
           double cube(Z, Y, X):
                  start file offset =       40512
                  end   file offset =     8040512
                  size in bytes     =     8000000
                  gap from prev var =           0

       record variables:
           double time(time):
                  start file offset =     8040512    (0th record)
                  end   file offset =     8040520    (0th record)
                  size in bytes     =           8    (of one record)
                  gap from prev var =           0
           float  rec_var(time, Z, Y, X):
                  start file offset =     8040520    (0th record)
                  end   file offset =    12040520    (0th record)
                  size in bytes     =     4000000    (of one record)
                  gap from prev var =           0
       }

       Check if there are gaps in between two adjacent fixed-size variables.

       % ncoffsets -x testfile.nc
       0

SEE ALSO

       pnetcdf(3)

DATE

       PNETCDF_RELEASE_DATE

Printed: 2025-11-27                      PnetCDF PNETCDF_RELEASE_VERSION                            ncoffsets(1)