[SOLVED] cronjob text output cut off

Issue

I have a cronjob that runs a python script every 2 hours. The script itself can run longer than 2 hours. Thats why I try to detect if the script is already running. The system is FreeBSD machine. I try to do the detection with the following function:

def script_already_running(script_name,console_logger,parameter=None):
    """
    checks if the script is already running, this is done by syscall and parsing the output. Parameters of the script can be distinguished as well
    """
    ps = subprocess.Popen("ps aux", shell=True, stdout=subprocess.PIPE)
    process_strings = ps.stdout.read().decode(encoding="utf-8",errors="strict")
    ps.stdout.close()
    ps.wait()
    console_logger.info(process_strings)
    # print(process_strings)
    # print(script_name)

    if script_name in process_strings and parameter is None:
        script_running = True
    elif script_name in process_strings and parameter is not None:
        if parameter in process_strings:
            script_running = True
        else:
            script_running = False
    else:
        script_running = False

    return script_running

this function is called from another script. script_name is the name (with path) of the calling script and console_logger is a python logging object. When I execute everything directly from the shell everything works just fine. The function prints the output of ps aux which looks like that (I removed the unnecessary rest)

USER    PID %CPU %MEM    VSZ    RSS TT  STAT STARTED       TIME COMMAND
mysql  7225 95.8  1.1 530948 190652  -  IJ   Sun12   3750:03.47 /usr/local/libexec/mysqld --defaults-extra-file=/var/db/mysql/my.cnf --basedir=/usr/local --datadir=/var/db/mysql --plugin-dir=/usr/local/lib/mysql/plugin --log-error=/var/db/mysql/test_jail.err --pid-
user  56261 22.8  0.4 195936  60040  0  S+J  22:14      0:02.74 python3 testscript.py (python3.6)
user  50756  0.6  0.5 220976  78068  -  SsJ  21:20      3:25.17 python3 /home/user/immoquery/src/testscript.py (python3.6)

So you can see it would never really run because when it starts it would always detect itself running. This is another problem I need to fix in the future. But when I look into the logs that the cronjob creates the output of ps aux looks like this:

USER    PID %CPU %MEM     VSZ     RSS TT  STAT STARTED       TIME COMMAND
mysql  7225 92,4  1,3  530948  224528  -  IJ   So.12   3179:35,23 /usr/local/li
user  80177 24,9  0,4  196016   60184  -  SsJ  09:20      0:02,83 python3 /home
user  68285  0,5  7,2 1343792 1198784  -  SsJ  07:20      6:46,38 python3 /home

An the check delivers false because it cannot find the script name in the string return of ps aux. The string is somehow cut off.

Here is the content of the cron file:

SHELL=/usr/local/bin/zsh
LANG=de_DE.UTF-8
LC_CTYPE="de_DE.UTF-8"
LC_COLLATE="de_DE.UTF-8"
LC_TIME="de_DE.UTF-8"
LC_NUMERIC="de_DE.UTF-8"
LC_MONETARY="de_DE.UTF-8"
LC_MESSAGES="de_DE.UTF-8"

# used to execute immobilienscout24 kaufangebote
#minute hour    mday    month   wday    command
20       7,9,11,13,15,17,19,21,23 *       *       *      python3 /home/user/immoquery/src/testscript.py >> /home/user/testscript.log 2>&1

Has anyone an idea how to fix this? Why is the process output cut off? Is there a virtual screen size or something involved?

Solution

You could keep it simple by doing something like:

0 */2 * * *  if ! pgrep -f your-script 2>&1 >/dev/null; then your-script; fi

The way it works is by checking if the process still running by using pgrep and if not it will run your script.

Answered By - nbari