Command works but permission denied error when executed from script

Question

The below command works fine from my localhost and I get the desired output. See below

$ ssh -o ConnectTimeout=7  -o BatchMode=yes [email protected] "echo WORKS;exit"
Output:
WORKS

Now, I put this command in a script file test.sh having sufficient execution privileges

$ cat test.sh
segment=$(ssh -o ConnectTimeout=7  -o BatchMode=yes [email protected] "echo WORKS;exit")
echo "SEGMENT $segment"

I don't get the desired output. Infact I get the below error:

$ ./test.sh
Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).
SEGMENT

I was expecting

SEGMENT WORKS

Now, the Permission denied error goes away but

Can you please suggest what could be the issue ?

How are you running your script (crontab?)? How are you authenticating with the remote system (public key in a ssh-agent?)? — Kusalananda, Commented Sep 24, 2020 at 8:37
@Kusalananda i updated my original post to answer your question. — Ashar, Commented Sep 24, 2020 at 8:51
I got the problem. alias ssh with private key ssh -i /<path_to_private_key> was set is what it was working on local command line but in the script I had to specify the private key explicitly. — Ashar, Commented Sep 24, 2020 at 8:58
Yes, aliases are not expanded in bash scripts. See e.g. unix.stackexchange.com/questions/368246/… — Kusalananda, Commented Sep 24, 2020 at 9:04
@Ashar you should write you solution as an answer, this might help someone in same situation. — Archemar, Commented Sep 24, 2020 at 9:14

AdminBee · Accepted Answer · 2020-09-25 07:42:23Z

1

The issue was that I used an alias

alias ssh=ssh -i /app/private_key

stored in the user profile. However, this setting doesn't take effect in a shell script (see here e.g.), so I had to explicitly call

ssh -i app/private_key

in the script. This resolved the issue.

AdminBee

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answered Sep 25, 2020 at 7:23

Ashar

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