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I have seen many softwares such as Update Manager and Synaptic Package Manager, they wait if some other program is using the /var/lib/dpkg/lock and is locked. How can we do this through the Terminal? I saw apt-get's manual but didn't find anything useful.

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5 Answers

up vote 11 down vote accepted

You can use the aptdcon command Manpage icon to queue up package manager tasks by communicating with aptdaemon instead of using apt-get directly.

So basically you can just do sudo aptdcon --install chromium-browser or whatever and while that command is running you can run it again but install different packages and apt-daemon will just queue them up instead of erroring out.

This is especially useful if you're doing a long upgrade or something and want to keep installing packages or if you're scripting something together and want to make sure installing things will be more reliable.

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Yeah! This works Thankyou! :) –  Piyush Jan 28 at 11:41
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You could using a polling technique:

$ time (while ps -opid= -C apt-get > /dev/null; do sleep 1; done); \
  apt-get -y install some-other-package
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I made a script which does this:


# File path to watch

# tput escape codes
cr="$(tput cr)"
clr_end="$(tput el)"
up_line="$(tput cuu 1)"

    # Cleans the last two lines of terminal output,
    # returns the cursor to the start of the first line
    # and exits with the specified value if not False

    echo -n "$cr$clr_end"
    echo -n "$cr$clr_end$up_line"
    if [[ ! "$1" == "False" ]]; then
        exit $1

    # Takes the LOCKED variable, expected to be output from `lsof`,
    # then gets the PID and command line from `/proc/$pid/cmdline`.
    # It sets `$open_program` to a user friendly string of the above.

    while IFS= read -d '' -r arg; do
    done < "/proc/${pid// }/cmdline"
    open_program="     $pid : ${cmdline[@]}"

# Default starting value

# Checks if the file is locked, writing output to $FUSER
while LOCKED="$(lsof -F p "$LOCK_FILE" 2>/dev/null)" ; do
    # This will be true if it isn't the first run
    if [[ "$i" != 0 ]]; then
        case $(($i % 4)) in
            0 ) s='-'
                _get_cmdline # Re-checks the command line each 4th iteration
            1 ) s=\\ ;;
            2 ) s='|' ;;
            3 ) s='/' ;;
        # Traps to clean up the printed text and cursor position
        trap "CLEAN False; trap - SIGINT ; kill -SIGINT $$" SIGINT
        trap 'CLEAN $((128+15))' SIGTERM
        trap 'CLEAN $((128+1))' SIGHUP
        trap 'CLEAN $((128+3))' SIGQUIT

        # Default starting character

        echo -n "$save_cur"
    # Prints the 2nd line first so the cursor is at the end of the 1st line (looks nicer)
    echo -n "$cr$clr_end$open_program"
    echo -n "$up_line$res_cur$cr$clr_end[$s] Waiting for other package managers to finish..."
    #echo -en "$cr$clr_end[$s] Waiting for other package managers to finish..."
    #echo -en "\n$cr$clr_end$open_program$cr$up_line"
    sleep 1.5


# This allows saving the script under a different name (e.g. `apt-wait`)
# and running it. It only imitates `apt-get` if it was launched as such
if [[ "${0##*/}" == 'apt-get' ]]; then
    exec /usr/bin/apt-get "$@"
    exit $?

Save the above into /usr/local/sbin/apt-get. apt-get will then wait if another instance is already running.

Alternatively, save it as /usr/local/sbin/apt-wait, example usage:

apt-wait && aptitude

which will run aptitude after the current process holding the lock has exited.

Example run:

  1. First, an apt-get command is run, (don't run this command):

    $ sudo apt-get remove apt
  2. Then, in another terminal, another command is run:

    $ sudo apt-get install apt

    It will wait for the first command to finish then run. Output while waiting:

    [/] Waiting for other package managers to finish...
          28223 : /usr/bin/apt-get remove apt
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Only one package manager can access the package directory while using apt-get. Either you have to quit an existing one to start a new one or you have to wait for one to finish to start a new one.

The commands corresponding to synaptic search and install are respectively "apt-cache search package" and "sudo apt-get install package".

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But how can we make it wait if other apt-get is running? –  Piyush May 5 '12 at 13:25
You'll have to wait manually or write a script that will start running the new apt-get once the old one is finished. But I don't understand a situation in which you would want to do that. Is there any problem manually waiting? Perhaps you could explain your situation so that we can help more. –  harisibrahimkv May 5 '12 at 13:28
It will help me in the situation when like I have lots of packages to download and suddenly I got an important call and I have to go somewhere. I want to complete the download by the time I return. But right now some other program is using the apt-get so I cannot start my download. –  Piyush May 6 '12 at 9:50
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As far as I know, you can select multiple packages from synaptic and also you can provide multiple packages to apt-get. So all you need to do, is to provide apt-get with all the packages you want to install, that should do the trick.

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