tcio(1)

Print a checksum to standard error. The checksum is a 32-bit unsigned addition of all bytes written to or read from the tape, providing an extra check of data validity (in addition to tape verification). The checksum value is only reported to the user, and is not written on the media; thus, the user must manually record and check it. The checksum is valid only if the same number of bytes are read from the tape as were written to it; in other words, the checksum as a data verification test is meaningless unless the -e option was used when writing the tape. This option is independent of the verbose modifier.

Cause a tape mark to be written on the nearest 1024-byte boundary following the end of the data. When a tape containing an end-of-data tape mark is read back, the read terminates upon encountering the tape mark. Thus, by using this option, the checksums generated by the input and output operations are guaranteed to agree.

Unload the tape from the drive. On autochanger units, the tape is returned to the magazine.

Verbose mode; prints information and error messages to standard error.

This option turns off tape verification. Some cartridge tape units (see DEPENDENCIES) provide hardware for verifying the data output to the tape (called "read-while-write"). For these units software-driven verification is somewhat redundant, and this option is suggested as a means of reducing wear on tape heads and transport mechanisms. However, read-while-write verification does not completely eliminate all risk of data loss, so software verification may still be desired in situations where data preservation is critically important.

For drives that do not have the read-while-write hardware, a separate verification operation is suggested. Thus, it is recommended that this option not be used with drives that do not support read-while-write.

Prevents tcio from writing a file mark in the first and last blocks. This option should be used with care because a tape without a tape mark in block zero can be image-restored to a disk.

This option is intended solely for autochanging tape drives. For input or output operations (-i or -o) the -l option selects the cartridge specified by number from the magazine as the first cartridge used in the transfer. For utility operations (-u option), tcio loads the cartridge specified by number into the drive. (Note: the autochanger must be in selective mode for the autochanger options to work properly.) Whitespace between -l and number is optional.

This option writes a tape mark on a tape at the specified block. A tape mark in block zero of the tape prevents it from being image-restored to a disk. Whitespace between -m and blocknumber is optional.

This option specifies the maximum number of cartridges to be allowed in a multitape transfer. It applies only to autochanger type units, and must be preceded by the -l option. Thus, -l starts the transfer by loading cartridge number and uses at most limit cartridges. If -l is specified without -n, tcio quietly assumes all remaining cartridges (in ascending order) in the magazine. Whitespace between -n and limit is optional.

Enable specification of buffer size. This option forces allocation of a block of memory to be used in reading or writing the tape. The size of the buffer in bytes is 1024 times the value specified for buffersize. If buffersize is less than 4, it is silently increased to 4. A buffersize greater than 64 is silently decreased to 64. If buffersize is not specified, tcio allocates a 64K-byte buffer. Whitespace between -S and buffersize is optional.

On tape units that support immediate report, a significant performance increase can often be obtained by using a smaller buffer. 8 Kbytes is the recommended buffer size for these units. On tape units that do not support the immediate report mode, or on tape units that share a controller with a disk (see DEPENDENCIES) that is simultaneously being accessed, an increase in performance can usually be obtained with a larger buffer. 64K bytes, the default, is the recommended buffer size for these units.

Specify tty as an alternative to /dev/tty. Normally /dev/tty is opened by tcio when terminal interaction is required. The specified file tty is opened instead of /dev/tty. Whitespace between -T and tty is optional. If no input device is available, use /dev/null.