secret key not available

[DODDI ANTHONY BALARAJU cs15d008]

 hI,

<http://stackoverflow.com/questions/37566637/why-showing-error-gpg-signing-failed#>
I'm new to this GPG usage. I dont need any internals. I am running a shell
script in which following line causes error :

gpg --yes --sign message.txt

It shows the following error:

gpg: no default secret key: secret key not available
gpg: signing failed: secret key not available

How can I solve this error, without modifying the command? (do I need to
change any settings). I am using gpg version (GnuPG) 1.4.16

>which gpg

is giving the output

/usr/bin/gpg

I Tried with --default-key <something>

Still it dint work!!

Any suggestion to get past this error will be greatly helpful.

Thank you
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