RMT(8)

# ✨ RMT(8) — rmt, the remote magnetic tape server ✨

## 💖 NAME 💖

okay so rmt is the remote magnetic tape server 🎀 it gives you remote access to files and devices for tar(1), cpio(1), and similar backup utilities 💅

## 🧚 SYNOPSIS 🧚

rmt

## 🦋 DESCRIPTION 🦋

bestie, rmt is the remote access queen 👑 it gives you remote access to files and devices for tar(1), cpio(1), and similar backup utilities. it's normally called by running rsh(1) or ssh(1) to the remote machine, and you can optionally use a different login name if one is supplied 🫶

the calling program talks to rmt by sending requests on its standard input and reading replies from the standard output ✨ a request is a request letter, then an argument (if it needs one), then a newline character. any extra data gets sent after the newline 💌

on success, rmt returns:

Anumber\n

where number is an ASCII representation of a decimal return code. any additional data comes back after this line 🌸 on error, you get this instead:

Eerrno\nerror-message\n

where errno is one of the system error codes, as described in errno(3), and error-message is a one-line human-readable description of the error, as printed by perror(3) 😭

the available commands and their possible responses are discussed in detail in the next section 🎀

# 💅 COMMANDS 💅

• Odevice\nflags\n — opens the device with the given flags 🔥 if a device was already open, it gets closed before the new one opens, so no drama 🙈

🎀 Arguments 🎀

• device — the name of the device to open.
• flags — flags for open(2): either a decimal number, or any valid O_* constant from fcntl.h (the initial O_ can be left off), or a bitwise or (using |) of any number of these, e.g.:

576
64|512
CREAT|TRUNC

the combined form is allowed too, meaning a decimal mode followed by its symbolic representation. when that happens, the symbolic representation gets the preference 💜

🦋 Reply 🦋

A0\n on success ✨

🌈 Extensions 🌈

the BSD version only allows a decimal number for flags 🥺

• C[device]\n — closes the currently open device 💖

🎀 Arguments 🎀

any arguments are silently ignored 🙈

🦋 Reply 🦋

A0\n on success ✨

• Lwhence\noffset\n — performs an lseek(2) on the currently open device with the specified parameters 🧚

🎀 Arguments 🎀

• whence — where to measure the offset from. valid values are:

0, SET, SEEK_SET   seek from the file beginning
1, CUR, SEEK_CUR   seek from the current location
2, END, SEEK_END   seek from the file end

🦋 Reply 🦋

Aoffset\n on success. the offset is the new offset in file 🫶

🌈 Extensions 🌈

the BSD version only allows 0, 1, 2 as whence 🥺

• Rcount\n — reads count bytes of data from the current device 📖

🎀 Arguments 🎀

• count — number of bytes to read.

🦋 Reply 🦋

on success, you get:

Ardcount\n

followed by rdcount bytes of data read from the device 💌

• Wcount\n — writes data onto the current device 📝 the command is followed by count bytes of input data.

🎀 Arguments 🎀

• count — number of bytes to write.

🦋 Reply 🦋

on success: Awrcount\n, where wrcount is the number of bytes actually written ✨

• Iopcode\ncount\n — performs a MTIOCOP ioctl(2) command with the specified paramedters 🍓

🎀 Arguments 🎀

• opcode — MTIOCOP operation code.
• count — mt_count.

🦋 Reply 🦋

on success: A0\n ✨

• S\n — returns the status of the currently open device, as obtained from a MTIOCGET ioctl(2) call 👀

🎀 Arguments 🎀

None

🦋 Reply 🦋

on success: Acount\n followed by count bytes of data 💖

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# 🌸 SEE ALSO 🌸

tar(1).

# 🙈 BUGS 🙈

using this utility as a general-purpose remote file access tool is discouraged 💀

# 🐛 BUG REPORTS 🐛

report bugs to <bug-tar@gnu.org> 💌

# 🍓 HISTORY 🍓

the rmt command appeared in 4.2BSD. the GNU rmt was written from scratch, using the BSD specification 🎀

# 🔥 COPYRIGHT 🔥

Copyright © 2013, 2018 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. 🫶

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bestie, that's the whole rmt manual, GNU TAR Manual edition, last touched March 24, 2018 ✨💖🦋 slay forever 💅🌈