mjhjmtu

is there any difference in the "Minimum number of days between password change" set to -1 and 0?

or maybe both commas does the same policy?

chage -m -1 user
chage -m 0 user

thank you for any hint, I can't find -1 descirbed in chage manual but it is possible to set it to -1

Minimum number of days between password change : -1

If you take a look at the source for chage there's a comment that explains what -1 does:

/*
 * new_fields - change the user's password aging information interactively.
 *
 * prompt the user for all of the password age values. set the fields
 * from the user's response, or leave alone if nothing was entered. The
 * value (-1) is used to indicate the field should be removed if possible.
 * any other negative value is an error. very large positive values will
 * be handled elsewhere.
 */

So when you specify chage -m -1 <user> it's disabling the mindays field. So disabling it with a -1 vs. setting it to 0 would appear to have the same effect, when it comes to restricting the how frequently a user can change their password.

References

• github repo - shadow/src/chage.c