con

A lightweight console utility for serial devices, TCP sockets, and UNIX domain sockets. A minimal minicom replacement with zero UI overhead. For serial and TCP usage modes, see the original README.

This document covers UDS client features used for EPICS IOC console access via procServ.

Build and Install

make
sudo make install DESTDIR=/usr/local
con -V

UDS Client Connection

Connect to a procServ IOC console:

con -c /run/procserv/myioc/control

Quiet mode suppresses connection banners:

con -c /run/procserv/myioc/control -q

Detach with Ctrl-A (default exit key).

Read-only Monitoring

Observe an IOC console without sending any keyboard input. Prevents accidental command injection when multiple operators share a console:

con -r -c /run/procserv/myioc/control

Ctrl-A exits. The exit key is always active in read-only mode.

Diagnostic Hotkey (Ctrl-T)

Press Ctrl-T during an active session to pause incoming data and display receive buffer utilization:

[diag] con recv buffer: 49152 / 212992 bytes (23%) - NORMAL
[diag] paused -- press any key to resume

Press any key to resume. Buffer status levels:

Level	Threshold	Action
NORMAL	< 50%	No action required
HIGH	50-80%	Check remote for output flood, consider con -r
		If EPICS IOC, check for device driver errors or crash-loop
CRITICAL	> 80%	Remote output may block, disconnect or reduce output rate
		If EPICS IOC, restart IOC or check procServ crash-loop

When logging is active (-l or -a), diagnostic output is also written to the log file.

Custom Exit Key

The default exit key is Ctrl-A (0x01). To change it to Ctrl-B:

con -x ctrl/b -c /run/procserv/myioc/control

The -x argument accepts ctrl/a, cntrl/a, control-a forms, or raw integer values (0x02, 002).

Accepted formats: ctrl/a, cntrl/a, control-a, or raw integer (0x02, 002).

Logging

Overwrite mode:

con -c /run/procserv/myioc/control -l session.log

Append mode with timestamped session header:

con -c /run/procserv/myioc/control -a session.log

Strip ANSI escape sequences from log output (for color-enabled EPICS shells):

con -c /run/procserv/myioc/control -n -l clean.log

Hex Output Modes

Hex bytes:

con -X -c /run/procserv/myioc/control

Hex + ASCII (non-printable shown as .):

con -Y -c /run/procserv/myioc/control

Switch Reference

Switch	Description
-V, --version	Print version, git hash, and build date
-h	Print help message
-c	Connect as UDS or TCP client
-r	Read-only mode
-q	Suppress connection banners
-l FILE	Log to file (overwrite)
-a FILE	Append to log file with session header
-n	Strip ANSI escape sequences from log
-X	Hex byte output
-Y	Hex + ASCII output
-x KEY	Custom exit key (default: Ctrl-A)
-e	Echo keyboard input locally
Ctrl-T	Diagnostic: pause and display buffer status
Ctrl-A	Exit session (default, configurable with -x)

Testing

make test

The Ctrl-T diagnostic hotkey is covered by make test (tests/test-uds-diag.bash). The interactive test below is for flood mode and visual inspection of the [diag] output:

bash tests/manual-test-diag-hotkey.bash          # echo mode
bash tests/manual-test-diag-hotkey.bash --flood   # flood mode

Test specifications: tests/README.md and tests/TEST_DETAILS.md.

Cross-compilation Example (BLM)

/srv/librablmOpt is the NFS folder where the BLM can access as PATH.

source ../deviceconf/BLM/setEnvBLMCC.bash
make clean
make
sudo make install DESTDIR=/srv/liberablmOpt