mt
Control magnetic tape drives
TLDR
Check the status of a tape drive
Rewind the tape to beginning
Move forward a given files, then position the tape on first block of next file
Rewind the tape, then position the tape at beginning of the given file
Position the tape at the end of valid data
Rewind the tape and unload/eject it
Write EOF (End-of-file) mark at the current position
SYNOPSIS
mt [-f device] operation [count]
PARAMETERS
-f device
Specifies the tape device to use. If omitted, the environment variable TAPE is consulted. Common values include /dev/st0, /dev/nst0 (non-rewinding), etc. The exact device name depends on the system configuration.
rewind
Rewinds the tape to the beginning.
offline
Rewinds the tape and puts the drive offline.
rewoffl
Same as offline, rewinds the tape and puts the drive offline.
erase
Erases the entire tape. Use with extreme caution!
fsf count
Forward space count files. Defaults to 1 if count is omitted.
bsf count
Backward space count files. Defaults to 1 if count is omitted.
fsr count
Forward space count records. Defaults to 1 if count is omitted.
bsr count
Backward space count records. Defaults to 1 if count is omitted.
weof count
Write count end-of-file marks. Defaults to 1 if count is omitted.
eom
Space to end of recorded media.
status
Displays the status of the tape drive.
tell
Displays the current block number of the tape drive.
DESCRIPTION
The mt command is a fundamental utility for interacting with magnetic tape drives in Linux and other Unix-like systems. It allows users to perform a wide array of operations, including rewinding, skipping files or records, writing end-of-file marks, and determining the status of the tape drive.
It is a crucial tool for backing up and restoring data to and from tape, as well as for archiving and data exchange. Proper use of mt requires understanding the specific tape drive being used and the format of the data on the tape. Incorrect usage can lead to data loss or corruption.
The command's behavior is often influenced by environment variables like TAPE, which specifies the default tape device to use if one isn't explicitly given on the command line. Because of the potential for serious data manipulation, it is important to exercise caution when using mt.
CAVEATS
Using mt incorrectly can lead to data loss. Always double-check the device name and the operation being performed before executing the command. Non-rewinding devices are often preferred for scripted operations to avoid unintended rewinds.
DEVICE NAMING CONVENTIONS
Tape devices are usually accessed through device files in the /dev directory. Rewinding devices (e.g., /dev/st0) automatically rewind the tape after each operation. Non-rewinding devices (e.g., /dev/nst0) leave the tape at its current position after each operation, which is useful for sequential operations.
ERROR HANDLING
The mt command can return different exit codes to indicate the success or failure of an operation. Consult the mt man page for details on the meaning of specific exit codes. Check the standard output/standard error for error messages.
HISTORY
The mt command has been a standard utility in Unix-like operating systems for many years, evolving alongside the development of magnetic tape technology. Its origins trace back to the early days of Unix, when tape drives were a primary means of data storage and backup. Over time, the command has been adapted and extended to support various tape drive models and formats. While tape usage has declined with the rise of disk-based storage, mt remains relevant for archival and specialized applications.
