Epics@GSI Webhome

Developers' Corner

Tips & Tricks and Examples

    seq Records Delay Timing and Processing

      seq-record.png

      • The calc record serves as a 10Hz Time reference.
      • The seq record:
        • is scanned every 10 s
        • each of the LNKx get its input value from the calc reference, delayed by DLYx
      • alert the seq record stays active until all LNKs have been processed.
      • alert the nested second, delayed, and "PPed" seq record "seq2" doesn't delay the execution of LNK4
      • alert LNK5 to a dummy record introduces an addditional delay, before "ai5" is "FLNKed" (Listing 1)
        otherwise (LNK5 undefined) "ai4" and "ai5" do get the (almost) same time (Listing 2)

      Listing 1
      > camonitor ai1 ai2 ai3 ai4 ai5 ai6
      ai1                            <undefined> 0 UDF INVALID
      ai2                            <undefined> 0 UDF INVALID
      ai3                            <undefined> 0 UDF INVALID
      ai4                            <undefined> 0 UDF INVALID
      ai5                            <undefined> 0 UDF INVALID
      ai6                            <undefined> 0 UDF INVALID
      
      ai1                            2015-06-12 11:20:43.537023 10.4  
      ai2                            2015-06-12 11:20:45.532220 12.4  
      ai3                            2015-06-12 11:20:45.927412 12.8  
      ai4                            2015-06-12 11:20:46.723239 13.6  
      ai5                            2015-06-12 11:20:50.718449 17.6  
      ai6                            2015-06-12 11:20:51.422657 18.3  
      
      ai1                            2015-06-12 11:20:53.548024 20.5  
      
      Listing 2
      > camonitor ai1 ai2 ai3 ai4 ai5 ai6
      ai1                            2015-06-12 11:34:01.036987 10.4  
      ai2                            2015-06-12 11:34:03.032172 12.4  
      ai3                            2015-06-12 11:34:03.427368 12.8  
      ai4                            2015-06-12 11:34:04.222552 13.6  
      ai5                            2015-06-12 11:34:04.222568 13.6  
      ai6                            2015-06-12 11:34:08.923422 18.3  
      
      ai1                            2015-06-12 11:34:11.037168 20.4  
      

    -- PeterZumbruch - 2017-03-31

    EpicsTipsAndTricksMultipleIOCs (edit)

    multiple IOCs

To have one PC / Computer per IOC/Server seems to be an annoying situation.
Solution would be to be able to have several IOCs running on a PC. But you will be faced by the following Problems
(taken from talk of Kenneth Evans: "_Channel Access in Depth_", Kenneth Evans, Jr., March 8, 2005 as Part of the EPICS “Getting Started” Lecture Series, p15):

Multiple Servers on the Same Host
  • Used to not be possible at all (Base 3.13)
  • Now, it can be done, but there are problems
  • Will get message
    • cas warning: Configured TCP port was unavailable. Using dynamically assigned TCP port 45003, but now two or more servers share the same UDP port. Depending on your IP kernel this server may not be reachable with UDP unicast (a host's IP in EPICS_CA_ADDR_LIST)
  • First part means clients will establish their circuit on another port than the default 5064.
    • Not a problem
  • Second part means unicast search requests may not get to both servers
    • UDP deficiency, similar to the CaRepeater problem
    • May be a problem when EPICS_CA_ADDR_LIST is used

    Solution 1: EPICS_CA_ADDR_LIST

    EPICS_CA_ADDR_LIST
    • Determines where to search
    • Is a list (separated by spaces)
      • “123.45.1.255 123.45.2.14 123.45.2.108”
    • Default is broadcast addresses of all interfaces on the host
      • Works when servers are on same subnet as clients
    • Broadcast address
      • Goes to all servers on a subnet
      • Example: 123.45.1.255
      • Use ifconfig –a on UNIX to find it (or ask an administrator)

By setting the EPICS_CA_ADDR_LIST, the EPICS Channel Access (Client) Address List on the client site.
E.g. for MEDM:
  1. export EPICS_CA_ADDR_LIST and start medm in the same session
    $> export EPICS_CA_ADDR_LIST && medm &

    Solution 2: make use of more EPICS environment variables to allow inter IOC communication

    Following the thread in tech-talk Multiple IOC from 2007:
       It was fixed by setting the CAS Beacon Address List to the address and ports of the other IOC's CA repeater port.
    
       IOC1
    
       EPICS_CAS_BEACON_ADDR_LIST=nnn.nnn.nnn.nnn:5071
       EPICS_CA_ADDR_LIST=nnn.nnn.nnn.nnn:5070
    
       IOC2
    
       EPICS_CA_Server_Port=5070
       EPICS_CAS_Server_Port=5070
       EPICS_CA_Repeater_Port=5071
       EPICS_CAS_BEACON_ADDR_LIST=nnn.nnn.nnn.nnn:5065
       EPICS_CA_ADDR_LIST=nnn.nnn.nnn.nnn:5064
    
    

-- PeterZumbruch - 2018-01-08

EpicsTipsAndTricksCrisAxisAddtionForSeveralEpicsApplications (edit)

cris-axis addition for several EPICS applications

HOWTO build flex (libfl) for cris-axis crisv32-axis

Since some of the EPICS extensions and modules rely on libfl flex and the standard distribution of AXIS SDK doesn't contain the libfl.a this has to be added:
Prerequisites
  • Axis SDK
  • cross compiler

Build & Installation

  1. set some helper variables:
    export SRC_DIR=<Source Directory>
    export DOWNLOAD_DIR=<Download Directory>
    # provided cross compiler and SDK are installed here export ETRAX_DIR=<ETRAX Tools Directory>
  2. download sources from http://sourceforge.net/projects/flex/ (version 2.5.35) via direct link to $DOWNLOAD_DIR
    mkdir -p ${DOWNLOAD_DIR:?undefined} &&
    wget http://prdownloads.sourceforge.net/flex/flex-2.5.35.tar.bz2?download
  3. unpack to $SRC_DIR
    mkdir -p ${SRC_DIR:?undefined} &&
    cd SRC_DIR &&
    tar -jxvf flex-2.5.35.tar.bz
  4. Source cris-axis-setup.sh ,defining environment variables, e.g. AXIS_TOP_DIR, and extending PATH, needs ETRAX_DIR to be defined. or just take its main code:
    oldpwd=$OLDPWD
    base=$(pwd)
    cd ${ETRAX_DIR:?undefined)/SDK && cd $(ls --color=never -t -1 -d devbo* | head -n 1) && . ./init_env
    cd $base
    cd ${ETRAX_DIR:?undefined)/ETRAX/compiler && . ./setup.sh
    cd $oldpwd
    cd $base
    unset scriptname base oldpwd epicsDir
  5. Change to source directory $SRC_DIR
    cd ${SRC_DIR:?undefined}
  6. Since configure automatically sets for cross-compilers 'ac_cv_func_malloc_0_nonnull' and 'ac_cv_func_realloc_0_nonnull' to 'no', (since it cannot check it) those have to be configured by hand:
    1. cris-axis
      1. export myTARGET=cris-axis-linux-gnu
      2. make clean
      3. ./configure --prefix=${AXIS_TOP_DIR:?undefined}/target/${myTARGET:?defined}/usr --host=${myTARGET} --build=i686-pc-linux-gnu ac_cv_func_realloc_0_nonnull=yes ac_cv_func_malloc_0_nonnull=yes
      4. make
      5. make install
    2. crisv32-axis
      1. export myTARGET=crisv32-axis-linux-gnu
      2. make clean
      3. ./configure --prefix=${AXIS_TOP_DIR:?undefined}/target/${myTARGET:?defined}/usr --host=${myTARGET} --build=i686-pc-linux-gnu ac_cv_func_realloc_0_nonnull=yes ac_cv_func_malloc_0_nonnull=yes
      4. make
      5. make install

    Compact
      export SRC_DIR=<Source Directory>
      export DOWNLOAD_DIR=<Download Directory>
      # provided cross compiler and SDK are installed here
      export ETRAX_DIR=<ETRAX Tools Directory>

      mkdir -p ${DOWNLOAD_DIR:?undefined} &&
      wget http://prdownloads.sourceforge.net/flex/flex-2.5.35.tar.bz2?download

      mkdir -p ${SRC_DIR:?undefined} &&
      cd SRC_DIR &&
      tar -jxvf flex-2.5.35.tar.bz

      oldpwd=$OLDPWD
      base=$(pwd)
      cd ${ETRAX_DIR:?undefined)/SDK && cd $(ls --color=never -t -1 -d devbo* | head -n 1) && . ./init_env
      cd $base
      cd ${ETRAX_DIR:?undefined)/ETRAX/compiler && . ./setup.sh
      cd $oldpwd
      cd $base
      unset scriptname base oldpwd epicsDir

      # crisv-axis
      export myTARGET=cris-axis-linux-gnu
      cd ${SRC_DIR:?undefined} &&
      make clean
      ./configure --prefix=${AXIS_TOP_DIR:?undefined}/target/${myTARGET:?defined}/usr --host=${myTARGET} --build=i686-pc-linux-gnu ac_cv_func_realloc_0_nonnull=yes ac_cv_func_malloc_0_nonnull=yes &&
      make && make install

      # crisv32-axis
      export myTARGET=crisv32-axis-linux-gnu
      cd ${SRC_DIR:?undefined} &&
      make clean
      ./configure --prefix=${AXIS_TOP_DIR:?undefined}/target/${myTARGET:?defined}/usr --host=${myTARGET} --build=i686-pc-linux-gnu ac_cv_func_realloc_0_nonnull=yes ac_cv_func_malloc_0_nonnull=yes &&
      make && make install

-- PeterZumbruch - 09 Apr 2009

-- PeterZumbruch - 2017-03-31

EpicsTipsAndTricksNewIocCommand (edit)

new IOC command

The general way how to add a new IOC command, which can be used inside the IOC Shell is described in Chapter 18.3 IOC Shell - IOC Shell Programming of the IOC Application Developer's Guide (3.14.9).

Here is an example (with the help of BK) to make the command dumpTable(mbo, dac, channel, type) available at the IOC shell.

  • application.c
      #include <epicsExport.h>
      
      /* ... */ 
      
      /***************************************************************************/
      static void dumpTable(int mbo, int dac, int channel, short type)
      {
              /* some function code */
              /* ... */ 
      }
      /***************************************************************************/
      
      /* Information needed by iocsh */
      /* Argument definition */
      static const iocshArg  dumpTableArg0 = {"mbo number",     iocshArgInt};
      static const iocshArg  dumpTableArg1 = {"dac number",     iocshArgInt};
      static const iocshArg  dumpTableArg2 = {"channel number", iocshArgInt};
      static const iocshArg  dumpTableArg3 = {"table type",     iocshArgInt};
      static const iocshArg  *dumpTableArgs[] = 
      {
              &dumpTableArg0,
              &dumpTableArg1,
              &dumpTableArg2,
              &dumpTableArg3
      };
      /* Function definition */
      static const iocshFuncDef dumpTableFuncDef = {"dumpTable", 4, dumpTableArgs};
      
      /* Wrapper called by iocsh, selects the argument types that dumpTable needs */
      static void dumpTableCallFunc(const iocshArgBuf *args) {
              dumpTable(args[0].ival, args[1].ival, args[2].ival, args[3].ival);
      }
      
      /* Registration routine, runs at startup */
      static void dumpTableRegister(void) {
              iocshRegister(&dumpTableFuncDef, dumpTableCallFunc);
      }
      epicsExportRegistrar(dumpTableRegister);

  • application.dbd
      variable(mySubDebug)
      ...
      registrar(dumpTableRegister)

-- PeterZumbruch - 08 May 2008

-- PeterZumbruch - 2018-01-08

EpicsTipsAndTricksUseOfMsiWithMultipleTempleateFiles (edit)

use of msi with multiple template files

To produce a single db file from multiple template files it is sufficient to include in the Makefile in the app/Db directory the line with the name of the db. This should be a not existing file (because it will be produced). Existing must be the corresponding substitutions file and the template file(s). In case that the substitutions file calls to a multiple template files is necessary to have an independent name from them, otherwise the generated db file will be only based on the same name template file.

Be aware that none of the template files should have the same name as the substitutions file.

Example: To make a db called vulom_1.db use a file vulom_1.substitutions which references for instance vulom.template, vulomreg.template, and vulomreg1.template

vulom_1.substitutions:
    file vulom.template {
    { PRE=HAD, NN="0", MM="1"}
    }
    file vulomreg.template {
    { PRE=HAD, NN="0", MM="1", CC="Del_0", AA="0", LIM="49.5", GAIN="3.3", LLIM="0"}
    { PRE=HAD, NN="0", MM="1", CC="Del_1", AA="1", LIM="49.5", GAIN="3.3", LLIM="0"}
    }
    file vulomreg1.template {
    { PRE=HAD, NN="0", MM="1", CC="Down_0", AA="7", LIM="15", GAIN="1"}
    { PRE=HAD, NN="0", MM="1", CC="Down_1", AA="8", LIM="15", GAIN="1"}
    }
    

The Makefile should contain a line
    DB += vulom_1.db
    

additional Dependencies

Adding the line in the Makefile
    vulom_1_DEPENDS ?= $(shell perl -n -e 'if (/file\s+(\w+.template)/) {print "$$1 \n";}' vulom_1.substitutions )
    
right after the previous
    DB += vulom_1.db
    
enables EPICS to check for dependencies (q.v. IOC Application Developer's Guide - 3.14.9 Chapter 4.6.4):
    If a <name> substitutions file contains "file" references to other input files, these referenced files should be made dependencies of the created <name>.db by adding a dependency definition line:
    <name>_DEPENDS = <filename1> <filename2> ...
-- PeterZumbruch - 09 May 2008

-- MartinMitkov - 2017-03-31

-- PeterZumbruch - 2018-01-08

-- PeterZumbruch - 2017-03-31

Applications & Use Cases


Windows tricks & tips

    Resize Raw Img File Using VirtualBox

    Following the recommendation on http://raspberrypi.stackexchange.com/questions/4943/resize-image-file-before-writing-to-sd-card:
    • e.g. to resize to 15.5GB, approx. size 15500
    set VBOXMANAGE="C:\Program Files\Oracle\VirtualBox\VBoxManage.exe"
    IF NOT EXIST %VBOXMANAGE% (
       echo %VBOXMANAGE% does not exist ... exiting)
    )
    ELSE (
    	IF EXIST input.vdi   ( %VBOXMANAGE% closemedium disk input.vdi --delete)
    	IF EXIST output.vdi ( %VBOXMANAGE% closemedium disk output.vdi --delete) 
    	IF EXIST output.img (%VBOXMANAGE% closemedium disk output.img)
    	 
    	REM  use without .img
    	set /p INPUT_NAME="Enter input file name without .img: "; 
    	set OUTPUT_NAME=%INPUT_NAME%_resized 
    	set /p OUTPUT_SIZE="Enter Size (MB) (e.g. 15000): "  
    	 
    	ECHO "=========================================================================" 
    	%VBOXMANAGE% convertfromraw %INPUT_NAME%.img input.vdi -format VDI --variant Standard 
    	ECHO "=========================================================================" 
    	%VBOXMANAGE% createhd --filename output.vdi --size %OUTPUT_SIZE% --format VDI --variant Standard 
    	ECHO "=========================================================================" 
    	%VBOXMANAGE% clonehd input.vdi output.vdi --existing 
    	ECHO "=========================================================================" 
    	%VBOXMANAGE% clonehd output.vdi output.img --format RAW 
    	copy output.img %OUTPUT_NAME%.img 
    	%VBOXMANAGE% closemedium disk input.vdi --delete 
    	%VBOXMANAGE% closemedium disk output.vdi --delete 
    	%VBOXMANAGE% closemedium disk output.img 
    )
    

    -- WikiGuest - 1970-01-01

    Windows: How To Clone A SD Card

    Following the help of page https://startingelectronics.org/articles/raspberry-PI/ten-things-raspberry-PI chapter 10.

    This video View on YouTube → shows how to clone a SD card in Windows

    -- WikiGuest - 1970-01-01

    -- WikiGuest - 1970-01-01

Linux tricks & tips

    serial device settings - switch off every possible hidden manipulation feature

    TippsSerialDeviceSettingsToSwitchOffEveryHiddenManipulation (edit)

    $> stty -F /dev/ttySx -opost -onlcr -isig -icanon -iexten -echo -echoe -echok -echoctl -echoke 19200

      • Output settings:
        -opost
        do not post-process output
        -onlcr
        do not translate newline to carriage return-newline
      • Local settings:
        -isig
        do not enable interrupt, quit, and suspend special characters
        -icanon
        do not enable erase, kill, werase, and rprnt special characters
        -iexten
        do not enable non-POSIX special characters
        -echo
        do not echo input characters
        -echoe
        do not echo erase characters as backspace-space-backspace
        -echok
        do not echo a newline after a kill character
        -echoctl
        do not echo control characters in hat notation ('^c')
        -echoke
        kill all line by obeying the echoctl and echok setting
        19200
        sets the speed to 19200 Bit/s

      Summarizing the settings prevent any additional manipulation of input or output.

    -- PeterZumbruch - 2017-11-30

    usbdev - dynamic device symlink and proper access rights

    udev/udevadm allows to automatically assign (fixed) symbolic links for USB devices connected to the system pointing the current /dev entry point.

    Prerequisites
    you have to have admin rights.

    How to
    • edit/create /etc/udev/rules.d/99-serial-permissions.rules
      • add the follwing line for general includes
        SUBSYSTEMS=="usb", ATTRS{idVendor}=="0403", SYMLINK+="$env{ID_SERIAL}", GROUP="users", MODE="0666"
        creates for every connected device of vendor id 0403 a symbolic link /dev/ to the connected device
      • for special devices those lines can be added in addition
        SUBSYSTEMS=="usb", ATTRS{idVendor}=="0403", ENV{ID_SERIAL}=="FTDI_FT232R_USB_UART_A100dQ2B", SYMLINK+="hadcon2", GROUP="users", MODE="0666"
        SUBSYSTEMS=="usb", ATTRS{idVendor}=="0403", ENV{ID_SERIAL}=="FTDI_FT232R_USB_UART_A600801P", SYMLINK+="olimex", GROUP="users", MODE="0666"

      • for special devices (e.g. HadCon2) those lines can be added in addition
        • SUBSYSTEMS=="usb", ATTRS{idVendor}=="0403", ENV{ID_SERIAL}=="FTDI_FT232R_USB_UART_A100*", RUN+="/usr/bin/stty -F /dev/$kernel -opost -onlcr -isig -icanon -iexten -echo -echoe -echok -echoctl -echoke 115200 "
        • SUBSYSTEMS=="usb", ATTRS{idVendor}=="0403", ENV{ID_SERIAL}=="FTDI_FT232R_USB_UART_A801*", RUN+="/usr/bin/stty -F /dev/$kernel -opost -onlcr -isig -icanon -iexten -echo -echoe -echok -echoctl -echoke 115200 "
    • to find out the IDs of connected systems
      udevadm info --export-db| grep FTDI| grep ID_SERIAL

    • Finally reload rules and trigger a reconnect:
      udevadm control --reload-rules
      udevadm trigger

    Links
    "Writing udev rules"
    http://reactivated.net/writing_udev_rules.html
    udev
    https://wiki.ubuntuusers.de/udev/
    "Tutorial on how to write basic udev rules in Linux"
    https://linuxconfig.org/tutorial-on-how-to-write-basic-udev-rules-in-linux

    -- PeterZumbruch - 2019-03-22

    SSH config: Host Specific Identity

    Using ssh config files in ~/.ssh/config allows to specify per host / host alias different user/identity to connect with and more necessary options.

    Using the features of the config file of ssh in ~/.ssh one can specify host specific ssh options, including varying identities and users.

    from: http://www.gelato.unsw.edu.au/archives/git/0611/31044.html

    Example:
    • connecting to a specific host using a different identity file and user
      $> cat ~/.ssh/config
         Host private.host.com
            User myname
            Hostname host.com
            IdentityFile ~/.ssh/private-identity
         Host public.host.com
            User anotherName
            Hostname host.com
            IdentityFile ~/.ssh/public-identity
         Host git.host.com
            User git
            Hostname host.com
            IdentityFile ~/.ssh/git-identity
           
    • allows to replace:
      • ssh host.com -l myname -i ~/.ssh/private-identity
        by
        ssh host.com
      • commands which internally use ssh but do not allow to pass ssh options, e.g. git
        git clone git.host.com

    -- PeterZumbruch - 2013-05-10

    Linux: dhclient - dynamic hostname

    Using dhclient exit hooks scripts allows to set e.g. the hostname dynamically

    Based on the articles: and its own origin

    dhclient and its scripting capabilities on enter and exit hooks allows to react on dynamic network environments.

    Provided you have root privileges this can be achieved by creating a script file hostname created in /etc/dhcp/dhclient-exit-hooks.d/ (on Debian), which is sourced by dhclient after having updated/received its DHCP informations.

    #!/bin/sh
       # Filename:     /etc/dhcp/dhclient-exit-hooks.d/hostname
       # Purpose:      Used by dhclient-script to set the hostname of the system
       #               to match the DNS information for the host as provided by
       #               DHCP.
       #
          
       # Do not update hostname for virtual machine IP assignments
       if [ "$interface" != "eth0" ] && [ "$interface" != "eth1" ] && [ "$interface" != "wlan0" ]
       then
               return
       fi
          
       if [ "$reason" != BOUND ] && [ "$reason" != RENEW ] && [ "$reason" != REBIND ] && [ "$reason" != REBOOT ]
       then
          return
       fi
       
       echo dhclient-exit-hooks.d/hostname: Dynamic IP address = $new_ip_address
       hostname=$(a=$(host $new_ip_address) || { false; } && { echo -n $a | cut -d ' ' -f 5 | cut -d "." -f 1; true; }) || unset hostname &&
       echo ${hostname?} > /etc/hostname &&
       hostname $hostname &&
       export HOSTNAME=$hostname &&
       echo dhclient-exit-hooks.d/hostname: Dynamic Hostname = $hostname
    

    Applying those code lines:
    sudo curl -s https://wiki.gsi.de/foswiki/pub/Epics/TipsLinuxDhclientDynamicHostname/_etc_dhcp_dhclient-exit-hooks.d_hostname -o /etc/dhcp/dhclient-exit-hooks.d/hostname && 
      sudo dos2unix /etc/dhcp/dhclient-exit-hooks.d/hostname && 
      sudo chmod a+r /etc/dhcp/dhclient-exit-hooks.d/hostname
    

    Local testing at the prompt:
    dhclient

    -- PeterZumbruch - 2018-11-30

    Linux: dhclient - dynamic mount point

    Using dhclient exit hooks scripts allows to set a mount point depending on the network environment, in this example for the HADES setup

    Based on the articles: and its own origin

    dhclient and its scripting capabilities on enter and exit hooks allows to react on dynamic network environments.

    Provided you have root privileges this can be achieved by creating a script file mount_var_diskless created in /etc/dhcp/dhclient-exit-hooks.d/ (on Debian), which is sourced by dhclient after having updated/received its DHCP informations.

    #!/bin/sh
    # Filename:     /etc/dhcp/dhclient-exit-hooks.d/mount_var_diskless
    # Purpose:      Used by dhclient-script to set mount HADES's var/diskless filesystem 
    #               from either the local net (preferred) or the GSI network
    #
    
    # Do not update hostname for virtual machine IP assignments
    if [ "$interface" != "eth0" ] && [ "$interface" != "eth1" ] && [ "$interface" != "wlan0" ]
    then
    return
    fi
    
    if [ "$reason" != BOUND ] && [ "$reason" != RENEW ] && [ "$reason" != REBIND ] && [ "$reason" != REBOOT ]
    then
    return
    fi
    
    var_diskless_hades=192.168.100.50
    var_diskless_gsi=140.181.75.158 
    var_diskless_path=/var/diskless/dreamplug
    var_diskless_mount=/var/diskless/dreamplug
    
    echo dhclient-exit-hooks.d/mount_var_diskless: new domain-name-servers: $new_domain_name_servers 
    
    echo "$new_domain_name_servers" | grep -q $var_diskless_hades && var_diskless_addr=$var_diskless_hades || var_diskless_addr=$var_diskless_gsi
    
    #clean up, but only different mounts
    grep -v "$var_diskless_addr:$var_diskless_path" /etc/mtab | grep -q "$var_diskless_mount" && umount $var_diskless_mount 
    
    #mount
    [ -d "$var_diskless_mount" ] || mkdir -p $var_diskless_mount
    grep "$var_diskless_addr:$var_diskless_path" /etc/mtab | grep -q "$var_diskless_mount" || mount $var_diskless_addr:$var_diskless_path $var_diskless_mount
    
    echo dhclient-exit-hooks.d/mount_var_diskless: mounted $var_diskless_addr:$var_diskless_path
    
    unset var_diskless_hades 
    unset var_diskless_gsi 
    unset var_diskless_path 
    unset var_diskless_mount
    

    Finally make sure the file is readable:
    chmod a+r /etc/dhcp/dhclient-exit-hooks.d/mount_var_diskless

    Local testing at the prompt:
    dhclient -v

    -- PeterZumbruch - 2013-10-21

    Linux: Hades Network - Allow Client To Connect Via Gateway

    To allow clients to connect outside of Hades network:
    • with root privileges
    ip r a default via 192.168.100.90 dev eth0

    -- WikiGuest - 1970-01-01

    Linux: How To Clone A SD Card

    Following the help of page https://startingelectronics.org/articles/raspberry-PI/ten-things-raspberry-PI chapter 10.

    This video View on YouTube → shows how to clone an SD card in Linux using the dd command line application.

    The command for copying an SD card to an image file on your computer is:
    sudo dd if=/dev/mmcblk0 of=~/raspi.img
    The command for copying an SD card image to a new SD card is:
    sudo dd if=~/raspi.img of=/dev/mmcblk0
    Where:
    • ~/raspi.img is the location and file name of the image file.
    • /dev/mmcblk0 is the SD card device on the Linux system.

    -- WikiGuest - 1970-01-01

    Linux: Resize Raw Img File

    see: http://www.vk3erw.com/index.php/16-software/33-raspberry-pi-how-to-resize-sd-card-image

    -- WikiGuest - 1970-01-01

    /sbin/reboot: Input/output error

    LinuxJournal-ReBootingTheMagicWay.png

    -- WikiGuest - 1970-01-01

    ProcServ: Remote Kill Via netcat

    ProcServ usually needs a login to its port to execute a "CTRL+X" sequence to kill/restart the current child process. Thanks to this cmdline it is also able without. Thanks to J.Michel / M.Traxler, afaik.

    Solution

    Assuming that procServ is running its telnet session on port 12345 on localhost
    echo -en "\x18" | netcat -w1 localhost 12345;
    

    -- WikiGuest - 1970-01-01

    -- WikiGuest - 1970-01-01

Hardware collection, evaluation


Git Tips & Tricks


-- PeterZumbruch - 11 Jun 2015
-- PeterZumbruch - 2017-03-31
Topic attachments
I Attachment Action Size Date Who Comment
cris-axis-setup.shsh cris-axis-setup.sh manage 0.8 K 2009-04-09 - 09:11 PeterZumbruch cris-axis-setup.sh: Bash script for cris-axis setup
Topic revision: r25 - 2017-03-31, PeterZumbruch
 
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