warning: commands will be executed using /bin/sh

hawksbill

Full Error: warning: commands will be executed using /bin/sh

What was being executed at the time?

$ at 07:38 < hw
warning: commands will be executed using /bin/sh
job 8 at Thu Nov 19 07:38:00 2020

Contents of hw script.

#!/bin/bash
echo "Hello World!" > at.log
ps -fp $$ >> at.log

Resolution.

This is default behavior of the at command. It will show no matter how you run the command.

       at and batch read commands from standard  input  or  a  specified  file
       which are to be executed at a later time, using /bin/sh.

Add #!/bin/bash at the top of your script.

If you need it to run as bash run the command like this:

$ echo /home/trainer/scripts/hw | at 09:02

Checking the output of the at execution in the log at.log, echo $$ shows the following

Hello World!
UID          PID    PPID  C STIME TTY          TIME CMD
trainer    24720   24719  0 09:01 ?        00:00:00 /bin/bash /home/trainer/scripts/hw