Add a User To Group Linux

Add a existing user to existing group :

To add an existing user jerry to sftpjail supplementary/secondary group with usermod command using -a option ~ i.e. add the user to the supplemental group(s). Use only with -G option:

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usermod -a -G sftpjail jerry

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To change existing jerry's primary group to lll, enter:

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usermod -g lll jerry 

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