Strange problem with crontab and echo

Question

$ echo -e "test1\ntest2" > logfile

$ echo -e "test1\ntest2" >> logfile

$ cat logfile
test1
test2
test1
test2

$ rm logfile

$ crontab -e
* * * * * echo -e "test1\ntest2" >> logfile

$ sleep 160

$ cat logfile
-e test1
test2
-e test1
test2

Why am I getting the -e in the output? Both crontab and bash are using /bin/echo

Solution 1

They're probably not both using /bin/echo. The environment used by cron is probably different from your interactive environment. Specify the full path to be sure.

Solution 2

This is one of the reasons people recommend using printf instead of echo for portability.

* * * * * printf "test1\ntest2\n" >> logfile

The shell that cron uses is sh rather than Bash. On my system, sh is really Dash and its echo doesn't have -e. So -e becomes just another string to be output. Other versions of the Bourne shell or shells that provide its functionality may have -e.

If you use echo without the full path in your crontab, you're getting the shell's builtin echo instead of /bin/echo. On the command line, if you're using Bash, then echo without the full path gives you Bash's builtin version.

Comments

[aidan]

well, before I tried this test, I tried another test: * * * * * which echo > logfile -- it showed the same thing as which echo

[aidan]

...but specifying the full path as you suggest does fix the problem. Strange?!

[Janne Pikkarainen]

aidan: "which" doesn't search for shell built-ins, it looks for files under $PATH. That's why "which echo" shows identical results, and that's why the interactive environment and cron can differ.

[labradort]

Golden rule of crons: Always use full paths. If you always follow the rule, you won't get something unexpected or borken.

[medina]

type echo should provide you some clarity here :)