Calling systemd's StartTransientUnit via DBus

transient_unit_start.sh

# Trying to use the following command and recieving:
#   Error: GDBus.Error:System.Error.ENXIO: No such device or address

# StartTransientUnit(in  s arg_0,
#                    in  s arg_1,
#                    in  a(sv) arg_2,
#                    in  a(sa(sv)) arg_3,
#                    out o arg_4);

gdbus call \
    --system \
    --dest org.freedesktop.systemd1 \
    --object-path /org/freedesktop/systemd1 \
    --method org.freedesktop.systemd1.Manager.StartTransientUnit \
        daharon-test.service \
        replace \
        "[('ExecStart', <'ls -h'>)]" \
        '[]'

Did you ever figure out why you got this error? This is the only result on this topic 😅

ExecStart isn't just a string, it's a a(sasb). The array contains commands (there can be more than one for some unit types). In each array element, the string is the pathname to execute and the array of strings is the arguments -- the information for a call to execve. The boolean is an "ignore failure" flag. See after /* Exec container */ in systemd-run run.c.