Serial and Telnet

sshc serial --json
sshc serial /dev/ttyUSB0 --baud 115200 --encoding utf-8

Serial options include data bits, parity, stop bits, DTR, RTS, and break duration. Flow control supports none, rtscts, and xonxoff. --dtr on|off and --rts on|off are applied once immediately after connecting; --break <duration> sends one break of the specified duration at that point. There are no controls to change them during the connection. These options are separate from flow control.

sshc telnet 192.0.2.20:23 --encoding shift_jis

Telnet is plaintext and does not authenticate the server. Limit it to a trusted isolated network or another protected boundary.

Serial and Telnet support utf-8, shift_jis, euc-jp, and iso-2022-jp. SSH encoding is saved per connection.

Non-interactive automation

sshc serial /dev/ttyUSB0 --non-interactive \
  --expect 'login:' --timeout 20s -- 'admin'

sshc telnet 192.0.2.20:23 --non-interactive \
  --script ./steps.json --json

--script cannot be combined with -- <text>, --expect, or --read-for: each step in the script file carries its own text and completion condition.

Non-interactive runs need exactly one completion condition: --expect succeeds when the regular expression matches, --read-for after reading for the given duration. Combine either with the overall --timeout, settle time, maximum bytes, line endings, and required output. JSON mode returns the result and any warnings in one object. Exit codes: 124 when the overall timeout elapses, 2 for invalid arguments, 1 for any other failure such as a transport error, and 130 when stopped by Ctrl+C, SIGTERM, or SIGHUP, including while still connecting.

Flags

Serial connection:

Flag	Value
--baud N	Speed, 1 to 4000000 (default 9600)
--data-bits N	Data bits: 5, 6, 7 or 8 (default 8)
--parity P	Parity: none, odd, even, mark or space
--stop-bits N	Stop bits: 1, 1.5 or 2
--flow F	Flow control: none, rtscts or xonxoff
--dtr on|off, --rts on|off	Set the line once, right after connecting
--break D	Send one break of this length (up to 5 seconds) right after connecting

Telnet connection:

Flag	Value
--connect-timeout D	How long to wait for the connection (default 10 seconds)
--terminal-type TYPE	Terminal type to tell the server (1 to 64 bytes)

Both:

Flag	Value
--encoding NAME	Character encoding: utf-8, shift_jis, euc-jp or iso-2022-jp
--non-interactive	Run as automation
--expect REGEX	Succeed when the output matches this regular expression
--read-for D	Succeed after reading for this long
--script FILE|-	Send each step of a script file (- for standard input) in turn
--timeout D	Overall limit; exceeding it exits with 124
--settle D	How long the output must stay quiet before it is taken as complete (0 to 5 seconds, default 120 ms)
--max-bytes N	Most bytes to read (default 1 MiB, up to 16 MiB)
--line-ending MODE	Line ending added after sent text: none, cr, lf or crlf
--require-output	Fail when nothing at all was received
--json	Print the result as JSON. sshc serial --json lists serial devices as JSON