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linuxshellserial-port
ARH
ARH

Reputation: 1395

Linux Shell, How to send a command over Serial port and return?

I am looking to send a 'reboot' command over the serial port to the PDU. What I have to do in the interactive mode is this:

#screen /dev/ttyS1
>reboot
>[Detach Screen]
#

If I want to automate this task in a script, I should be able to reboot the PDU with a single command from shell like this:

#echo "reboot" >/dev/ttyS1

However, it does not work ! I don't know why.... Would you be able to help me ?

The PDU manual request baud rate of 9600 which is not a default baud rate. I have tried following command to set the baud rate but still no lock:

stty -F /dev/ttyS1 speed 9600 cs8 -cstopb -parenb

These outputs does not change with or without screen:

 # stty -a -F /dev/ttyS1
    speed 9600 baud; rows 0; columns 0; line = 0;
    intr = ^C; quit = ^\; erase = ^?; kill = ^H; eof = ^D; eol = <undef>;
    eol2 = <undef>; swtch = <undef>; start = ^Q; stop = ^S; susp = ^Z;     rprnt = ^R;
    werase = ^W; lnext = ^V; flush = ^O; min = 100; time = 2;
    -parenb -parodd cs8 -hupcl -cstopb cread clocal -crtscts
    -ignbrk brkint ignpar -parmrk -inpck -istrip -inlcr -igncr -icrnl ixon    -ixoff
    -iuclc -ixany -imaxbel -iutf8
    -opost -olcuc -ocrnl -onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0
    -isig -icanon iexten -echo echoe echok -echonl -noflsh -xcase -tostop -echoprt
    echoctl echoke

Upvotes: 4

Views: 16953

Answers (1)

ARH
ARH

Reputation: 1395

Here is how we fixed this issue:

  1. Config serial port with RAW setting:

    stty -F /dev/ttyS1 speed 9600 cs8 -cstopb -parenb raw

  2. Send Command using echo with \r:

    echo -ne "reboot\r" > /dev/ttyS1

I believe that the above might include a typo. If the above doesn't work, try:

 echo -ne "reboot\n\r" > /dev/ttyS1

Upvotes: 5

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