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Thread: part of bash script doesn't execute when triggered by udev rule

  1. #1
    Join Date
    Jan 2021
    Beans
    5

    part of bash script doesn't execute when triggered by udev rule

    hello,

    I'm on Ubuntu 18.04.5 LTS and I wrote a script to take pictures and send an email with ssmtp when someone removes a USB device from my computer.
    the udev rule works fine and execute the script but only the "picture taking" part works, not the email sending.
    when I execute the script myself in a terminal, everything goes well, the pictures are taken, the email is sent. It just doesn't work when it is triggered by the udev rule.
    the rule:

    Code:
     ACTION=="remove", SUBSYSTEM=="usb", RUN+="/home/jensen/Documents/script.sh"
    the script:

    Code:
    #!/bin/bash
    
    cd /home/jensen
    fswebcam -r 640x480 --jpeg 85 webcamshot1.jpg
    fswebcam -r 640x480 --jpeg 85 webcamshot2.jpg
    fswebcam -r 640x480 --jpeg 85 webcamshot3.jpg
    
    echo "Subject: test mail" | /usr/sbin/sendmail -v testmail@gmail.com
    
    and the ssmtp config:

    Code:
    root=**********@gmail.com
    mailhub=smtp.gmail.com:587
    hostname=jensen
    AuthUser=**********@gmail.com
    AuthPass=**********
    UseSTARTTLS=yes
    UseTLS=yes
    FromLineOverride=yes
    I tried changing the permissions on the script file with chmod but nothing works. what could be the issue ?

    Another precision, I can create a new folder with my script with mkdir but if I try the following code, nothing happen
    Code:
     "spd-say 'something'
    Last edited by pidou66; January 16th, 2021 at 02:15 PM.

  2. #2
    Join Date
    Jun 2018
    Beans
    141

    Re: part of bash script doesn't execute when triggered by udev rule

    These types of issues are almost always related to a missing environment or parts thereof. According to this link the sendmail command requires an environment variable which points to the location where the config file is located, so try to set it explicitly like this:

    Code:
    #!/bin/bash cd /home/jensen
    fswebcam -r 640x480 --jpeg 85 webcamshot1.jpg
    fswebcam -r 640x480 --jpeg 85 webcamshot2.jpg
    fswebcam -r 640x480 --jpeg 85 webcamshot3.jpg
    
    export MAIL_CONFIG=/path/to/config
    
    echo "Subject: test mail" | /usr/sbin/sendmail -v testmail@gmail.com

  3. #3
    Join Date
    Jan 2021
    Beans
    5

    Re: part of bash script doesn't execute when triggered by udev rule

    yes but why would it work fine when I execute it myself via a terminal ?
    what is the difference between executing the script myself and a rule executing it ?

  4. #4
    Join Date
    Jun 2018
    Beans
    141

    Re: part of bash script doesn't execute when triggered by udev rule

    Because the terminal is run with a full environment, you can try to put this in the script:

    Code:
    env > /home/jensen/env.txt
    And check if there is any difference in the environment from the console and the udev rule.

  5. #5
    Join Date
    Jan 2021
    Beans
    5

    Re: part of bash script doesn't execute when triggered by udev rule

    I juste edited my last reply, I didn't understood the use of the line you sent me at first. here are the results :

    env.txt when the usb device is removed:

    Code:
    ACTION=remove
    USEC_INITIALIZED=7702106033
    SUBSYSTEM=usb
    SEQNUM=3463
    BUSNUM=002
    TYPE=0/0/0
    DEVPATH=/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.1
    PWD=/
    MINOR=141
    DEVTYPE=usb_device
    MAJOR=189
    DEVNAME=/dev/bus/usb/002/014
    SHLVL=1
    PRODUCT=46d/c077/7200
    DEVNUM=014
    _=/usr/bin/env
    env.txt when I execute the code in a terminal :

    Code:
    CLUTTER_IM_MODULE=xim
    LS_COLORS=rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:mi=00:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arc=01;31:*.arj=01;31:*.taz=01;31:*.lha=01;31:*.lz4=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.tzo=01;31:*.t7z=01;31:*.zip=01;31:*.z=01;31:*.Z=01;31:*.dz=01;31:*.gz=01;31:*.lrz=01;31:*.lz=01;31:*.lzo=01;31:*.xz=01;31:*.zst=01;31:*.tzst=01;31:*.bz2=01;31:*.bz=01;31:*.tbz=01;31:*.tbz2=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.war=01;31:*.ear=01;31:*.sar=01;31:*.rar=01;31:*.alz=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.cab=01;31:*.wim=01;31:*.swm=01;31:*.dwm=01;31:*.esd=01;31:*.jpg=01;35:*.jpeg=01;35:*.mjpg=01;35:*.mjpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.webm=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.m4a=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.oga=00;36:*.opus=00;36:*.spx=00;36:*.xspf=00;36:
    LC_MEASUREMENT=fr_FR.UTF-8
    LESSCLOSE=/usr/bin/lesspipe %s %s
    LC_PAPER=fr_FR.UTF-8
    LC_MONETARY=fr_FR.UTF-8
    TERMINATOR_UUID=urn:uuid:9462136c-4e92-4fe1-b0cd-c81922e89d14
    XDG_MENU_PREFIX=gnome-
    _=/usr/bin/env
    LANG=en_US.UTF-8
    DISPLAY=:0
    OLDPWD=/home/jensen
    GNOME_SHELL_SESSION_MODE=ubuntu
    COLORTERM=truecolor
    USERNAME=jensen
    XDG_VTNR=2
    GIO_LAUNCHED_DESKTOP_FILE_PID=2324
    SSH_AUTH_SOCK=/run/user/1000/keyring/ssh
    LC_NAME=fr_FR.UTF-8
    XDG_SESSION_ID=2
    USER=jensen
    DESKTOP_SESSION=ubuntu
    QT4_IM_MODULE=xim
    TEXTDOMAINDIR=/usr/share/locale/
    PWD=/home/jensen/Documents
    HOME=/home/jensen
    TEXTDOMAIN=im-config
    SSH_AGENT_PID=1697
    QT_ACCESSIBILITY=1
    XDG_SESSION_TYPE=x11
    XDG_DATA_DIRS=/usr/share/ubuntu:/usr/local/share/:/usr/share/:/var/lib/snapd/desktop
    TERMINATOR_DBUS_NAME=net.tenshu.Terminator20x1a6021154d881c
    XDG_SESSION_DESKTOP=ubuntu
    LC_ADDRESS=fr_FR.UTF-8
    GJS_DEBUG_OUTPUT=stderr
    LC_NUMERIC=fr_FR.UTF-8
    GTK_MODULES=gail:atk-bridge
    TERMINATOR_DBUS_PATH=/net/tenshu/Terminator2
    WINDOWPATH=2
    SHELL=/bin/bash
    VTE_VERSION=5202
    TERM=xterm-256color
    QT_IM_MODULE=xim
    XMODIFIERS=@im=ibus
    IM_CONFIG_PHASE=2
    XDG_CURRENT_DESKTOP=ubuntu:GNOME
    GPG_AGENT_INFO=/run/user/1000/gnupg/S.gpg-agent:0:1
    GIO_LAUNCHED_DESKTOP_FILE=/usr/share/applications/terminator.desktop
    SHLVL=2
    XDG_SEAT=seat0
    LC_TELEPHONE=fr_FR.UTF-8
    GDMSESSION=ubuntu
    GNOME_DESKTOP_SESSION_ID=this-is-deprecated
    LOGNAME=jensen
    DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus
    XDG_RUNTIME_DIR=/run/user/1000
    XAUTHORITY=/run/user/1000/gdm/Xauthority
    XDG_CONFIG_DIRS=/etc/xdg/xdg-ubuntu:/etc/xdg
    PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin
    LC_IDENTIFICATION=fr_FR.UTF-8
    GJS_DEBUG_TOPICS=JS ERROR;JS LOG
    SESSION_MANAGER=local/jensen-Aspire-E1-531:@/tmp/.ICE-unix/1602,unix/jensen-Aspire-E1-531:/tmp/.ICE-unix/1602
    LESSOPEN=| /usr/bin/lesspipe %s
    GTK_IM_MODULE=ibus
    LC_TIME=fr_FR.UTF-8
    Last edited by pidou66; January 16th, 2021 at 01:29 PM.

  6. #6
    Join Date
    Jun 2018
    Beans
    141

    Re: part of bash script doesn't execute when triggered by udev rule

    There is a big difference in the two environments, so now you know why there is a difference from inside the terminal and outside. Try to change the permissions of the script so it belongs to root. If that does nothing, try to run the script as your user by changing the udev rule to use "su" to change user:

    Code:
    ACTION=="remove", SUBSYSTEM=="usb", RUN+="/bin/su jensen -c '/home/jensen/Documents/script.sh'"

  7. #7
    Join Date
    Jan 2021
    Beans
    5

    Re: part of bash script doesn't execute when triggered by udev rule

    I just edited my rule with " /bin/su jensen -c '/home/jensen/Documents/script.sh' "and it works perfectly, thank you so much !

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