gpg --list-key rms46@ui.ac.id
gpg --sign-key rms46@ui.ac.id
gpg --list-key rms46@ui.ac.id

$ gpg --list-key rms46@ui.ac.id
pub   rsa4096 2022-02-07 [SC] [expires: 2023-02-07]
      055FEB594B351CC03DE992C563FB12B215403B20
uid           [ unknown] RMS46 (RMS46) <rms46@ui.ac.id>
sub   rsa4096 2022-02-07 [E] [expires: 2023-02-07]

$ gpg --sign-key rms46@ui.ac.id
gpg (GnuPG) 2.2.27; Copyright (C) 2021 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

pub  rsa4096/63FB12B215403B20
     created: 2022-02-07  expires: 2023-02-07  usage: SC  
     trust: unknown       validity: unknown
sub  rsa4096/CE5731A8D211C243
     created: 2022-02-07  expires: 2023-02-07  usage: E   
[ unknown] (1). RMS46 (RMS46) <rms46@ui.ac.id>

gpg> sign

pub  rsa4096/63FB12B215403B20
     created: 2022-02-07  expires: 2023-02-07  usage: SC  
     trust: unknown       validity: unknown
 Primary key fingerprint: 055F EB59 4B35 1CC0 3DE9  92C5 63FB 12B2 1540 3B20

     RMS46 (RMS46) <rms46@ui.ac.id>

This key is due to expire on 2023-02-07.
Are you sure that you want to sign this key with your
key "Cicak Bin Kadal (CBK) <cbkadal@localhost>" (60914D29C01C81F1)

Really sign? (y/N) y

gpg> save

$ gpg --list-key rms46@ui.ac.id

gpg: checking the trustdb
gpg: marginals needed: 3  completes needed: 1  trust model: pgp
gpg: depth: 0  valid:   1  signed:   1  trust: 0-, 0q, 0n, 0m, 0f, 1u
gpg: depth: 1  valid:   1  signed:   0  trust: 1-, 0q, 0n, 0m, 0f, 0u
gpg: next trustdb check due at 2023-02-07
/home/cbkadal/.gnupg/pubring.kbx
--------------------------------
pub   rsa4096 2021-09-11 [SC] [expires: 2023-02-07]
      CE17E9DB8AD01794E3BAE98B60914D29C01C81F1
uid           [ultimate] Cicak Bin Kadal (CBK) <cbkadal@localhost>
sub   rsa4096 2021-09-11 [E] [expires: 2023-02-07]

pub   rsa4096 2022-02-07 [SC] [expires: 2023-02-07]
      055FEB594B351CC03DE992C563FB12B215403B20
uid           [  full  ] RMS46 (RMS46) <rms46@ui.ac.id>
sub   rsa4096 2022-02-07 [E] [expires: 2023-02-07]