Grep binary files for ascii text

The phasta files (restart and geombc) include ascii headers, potentially (but not necessarily) followed by an associated binary block of data. A good example is the solution field in a restart file whose header typically looks like this:

 solution : < 60193 > 1254 6 0 

For the short story,

• if the number between <> is larger than 0, it means this header is followed by a data block in binary format. In this case, this number between <> represents the size of the data block in bytes -1.
• The following numbers are peculiar to the header but for most of the fields in the restart files, the first number after the > sign represents the number of vertices in the considered mesh part (here 1254).
• Then, 6 represents the number of variables per nodes.
• Finally the last number (0 here) is the time step.

Do the math: 1254 vertices * 6 variables per vertex * 8 bytes for a double = 60194.

Listing the headers included in your phasta files may be very useful. For that purpose, use the following command for instance:

grep -a ' : < ' restart.0.1 

It will search for the ascii text ' : < ' (space : space < space) in the hybrid ascii - binary file restart.0.1. Note that the key ' : < ' is common to any header included in the geombc or restart files.

The output will look like this for instance:

 byteorder magic number : < 5 > 1
 number of modes : < 0 > 1254
 number of variables : < 0 > 6 
 solution : < 60193 > 1254 6 0 
 mapping_partid : < 10033 > 1254 1 0 
 mapping_vtxid : < 10033 > 1254 1 0