mtexamine: Examine the structure of a magnetic tape

Package: dataio

Usage

mtexamine tape_file

Parameters

tape_file: Tape or disk file, e.g. "mta1600[2]", "mta1600" or "data".

file_list = "1-999": List of tape file numbers or ranges delimited by commas, e.g. "1-3,5-8". File_list is used only if no file number is given in tape_file. Files will be read in ascending order, regardless of the order of the list. Reading will terminate if EOT is reached, thus a list such as "1-999" may be used to read all the files on the tape. File_list is ignored is input is a single disk file.

dump_records = no: Dump selected records?

rec_list = "1-999": List of tape record numbers or ranges to be dumped delimited by whitespace or commas e.g "1-3,4".

swapbytes = no: Swap bytes?

byte_chunk = 1: The number of bytes which are considered as one output element. The maximum number of bytes permitted in byte_chunk is the number of bytes in a long integer on the host machine.

output_format = "o": Permitted types are character(c), octal(o), hexadecimal (x), decimal (d) or unsigned decimal (u). Character dumps are only permitted for byte_chunk = 1. Unless decimal format is specified, the data are dumped as unsigned integers.

Description

By default mtexamine determines the record structure of all files on a magnetic tape or a single disk file. Selected files can be dumped by setting the file_list parameter. Selected records can be dumped by setting the dump_record switch and entering a record list. The user can select the byte chunk and the output format for the dump.

Mtexamine can also be used to dump a single disk file. However the concept of a block is not well defined for disk files. Mtexamine defines a block to be one IRAF file io block which is usually some multiple of the machine block size.

Examples

1. Determine the record structure of a magnetic tape and send the result to the file tapedump.

cl> mtexamine mtb1600 > tapedump

2. Dump the third tape file in octal bytes on the standard output.

cl> mtexamine mtb1600[3] du+

3. Dump the contents of the fifth record of the third tape file in ASCII characters on the standard output.

cl> mtexamine mtb1600[3] du+ re=5 ou=c

Bugs

The IRAF magtape i/o routines do not permit data beyond a double EOF to be accessed. Therefore mtexamine cannot be used to examine tapes with embedded double EOFs.