hitting C-s - Unix

This is a discussion on hitting C-s - Unix ; I hit C-s on the command line of an xterm on Linux box. The xterm hangs. Only way i have found to un-suspend is to kill xterm. I'm assuming C-s is for suspend....

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  1. hitting C-s

    I hit C-s on the command line of an xterm on Linux box. The xterm hangs.
    Only way i have found to un-suspend is to kill xterm.
    I'm assuming C-s is for suspend.



  2. Re: hitting C-s

    Billy Patton wrote:
    > I hit C-s on the command line of an xterm on Linux box. The xterm hangs.
    > Only way i have found to un-suspend is to kill xterm.
    > I'm assuming C-s is for suspend.
    >
    >


    Try control-q

  3. Re: hitting C-s

    On 2007-05-30, Billy Patton wrote:

    > I hit C-s on the command line of an xterm on Linux box. The xterm hangs.
    > Only way i have found to un-suspend is to kill xterm.
    > I'm assuming C-s is for suspend.


    Hit C-q to resume (I'm not sure why it's "q" for "resume").

  4. Re: hitting C-s

    In article ,
    Adam Funk wrote:

    > On 2007-05-30, Billy Patton wrote:
    >
    > > I hit C-s on the command line of an xterm on Linux box. The xterm hangs.
    > > Only way i have found to un-suspend is to kill xterm.
    > > I'm assuming C-s is for suspend.

    >
    > Hit C-q to resume (I'm not sure why it's "q" for "resume").


    These codes were not originally intended for interactive use, they were
    for flow control to slow teletype devices. The original assignment of
    ASCII control characters has virtually no mnemonic association.

    --
    Barry Margolin, barmar@alum.mit.edu
    Arlington, MA
    *** PLEASE post questions in newsgroups, not directly to me ***
    *** PLEASE don't copy me on replies, I'll read them in the group ***

  5. Re: hitting C-s

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    Barry Margolin wrote:
    > In article ,
    > Adam Funk wrote:
    >
    >> On 2007-05-30, Billy Patton wrote:
    >>
    >>> I hit C-s on the command line of an xterm on Linux box. The xterm hangs.
    >>> Only way i have found to un-suspend is to kill xterm.
    >>> I'm assuming C-s is for suspend.

    >> Hit C-q to resume (I'm not sure why it's "q" for "resume").

    >
    > These codes were not originally intended for interactive use, they were
    > for flow control to slow teletype devices. The original assignment of
    > ASCII control characters has virtually no mnemonic association.


    On the TeleType ASR33 (the type of terminal used in early Unix systems), you
    could have a Paper Tape reader and a Paper Tape punch. These two peripherals
    were "substitutes" for the tty, in that the paper tape reader would, when
    active, pass it's data to the system as if it had been typed in at the tty,
    and the paper tape punch, when active, would record what ever was printed by
    the tty.

    TeleType made these two devices respond to the ASCII Device Control codes, so
    that the host system could control them. Unix had support for these devices
    built in to the terminal line conditioning code. The controlcodes that
    manipulated the devices were:

    ^P = DC1 (ASCII Device Control 1) = Paper Tape Reader ON (resume reading)
    ^Q = DC2 (ASCII Device Control 2) = Paper Tape Punch ON (resume writing)
    ^R = DC3 (ASCII Device Control 3) = Paper Tape Reader OFF (suspend reading)
    ^S = DC4 (ASCII Device Control 4) = Paper Tape Punch OFF (suspend writing)

    These control codes came in handy when people wanted to suspend and resume
    output. ^S would turn off the punch (suspend output to the punch), and ^Q
    would cause it to resume. I guess the Bell Labs guys decided that Unix should
    also use these controlcodes to suspend and resume output to the terminal.

    - --
    Lew Pitcher

    Master Codewright & JOAT-in-training | Registered Linux User #112576
    http://pitcher.digitalfreehold.ca/ | GPG public key available by request
    - ---------- Slackware - Because I know what I'm doing. ------


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  6. Re: hitting C-s

    Barry Margolin wrote:

    > These codes were not originally intended for interactive use, they were
    > for flow control to slow teletype devices. The original assignment of
    > ASCII control characters has virtually no mnemonic association.


    They're the XON/XOFF codes, which don't have _any_ mneominic association
    with ASCII. The control characters in question are in the Device Change
    block and have no predefined meaning under ASCII. The XON/XOFF meaning
    evolved later, and persists today, hence the ^S and ^Q without any
    seeing pattern.

    --
    Erik Max Francis && max@alcyone.com && http://www.alcyone.com/max/
    San Jose, CA, USA && 37 20 N 121 53 W && AIM, Y!M erikmaxfrancis
    But why should I turn on love / When it's never turned on me
    -- Syleena Johnson

  7. Re: hitting C-s

    On 2007-05-30, Barry Margolin wrote:

    >> > I hit C-s on the command line of an xterm on Linux box. The xterm hangs.
    >> > Only way i have found to un-suspend is to kill xterm.
    >> > I'm assuming C-s is for suspend.

    >>
    >> Hit C-q to resume (I'm not sure why it's "q" for "resume").

    >
    > These codes were not originally intended for interactive use, they were
    > for flow control to slow teletype devices. The original assignment of
    > ASCII control characters has virtually no mnemonic association.


    Aha, I thought the person who first defined it was aiming for a
    different key and missed.


  8. Re: hitting C-s

    In article ,
    Erik Max Francis wrote:

    > Barry Margolin wrote:
    >
    > > These codes were not originally intended for interactive use, they were
    > > for flow control to slow teletype devices. The original assignment of
    > > ASCII control characters has virtually no mnemonic association.

    >
    > They're the XON/XOFF codes, which don't have _any_ mneominic association
    > with ASCII. The control characters in question are in the Device Change
    > block and have no predefined meaning under ASCII. The XON/XOFF meaning
    > evolved later, and persists today, hence the ^S and ^Q without any
    > seeing pattern.


    I'm not sure what point you're trying to make. My point was that no
    ASCII control codes have mnemonic meanings. There's no mnemonic reason
    why TAB is ^I, CR is ^M, FF is ^L, etc. The binary codes were assigned
    without worrying about what they corresponded to when typed on the
    keyboard (I suspect the ability to type them was not even envisioned
    originally).

    --
    Barry Margolin, barmar@alum.mit.edu
    Arlington, MA
    *** PLEASE post questions in newsgroups, not directly to me ***
    *** PLEASE don't copy me on replies, I'll read them in the group ***

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