Latin tenses in commands (semantics)
Imperative clauses represent actions to be carried out (read more on Imperative mood). While indicated events are placed in a timeline relative to the speech act (past, present, future), imperated actions do not vary for a primary tense: i.e. imperated actions can be carried out only after the speech act (future). However, a task can be placed in a temporal circumstance relative to another event -- after, while or before that event -- which means imperative clauses may have a secondary tense. Primary tense

Positive commands 
The present imperative mood is the normal tense used for giving direct orders which the speaker wishes to be carried out at once. The active form can be made plural by adding -te:
 (Catullus)
'give me a thousand kisses, then a hundred!' (Livy)
'give me your right hands and your oath!' Deponent verbs such as  'I set out' or  'I follow' have an imperative ending in -re or -minī (plural):
 (Cicero)
'the gates are open: depart!' (Terence)
'follow me this way inside, both of you'

The future can also be used for polite requests, as when Cicero sends greetings to his friend Atticus's wife and daughter:
 (Cicero)
'please give my greetings to Pilia and Attica'

Negative commands 
An imperative is usually made negative by using  (literally, 'be unwilling!') plus the infinitive:
 (Seneca the Elder)
'don't be surprised'

However, in poetry an imperative can sometimes be made negative with the particle nē:
 (Virgil)
'do not terrify me, who am already scared, obscene birds!' A negative order can also use the perfect subjunctive: 
 (Cicero)
'do not be afraid on my account'

In later Latin,  plus the present subjunctive became more common, for example in the Vulgate Bible. In the following example the first three verbs use the present subjunctive, and the third the perfect subjunctive:
 (Mark, 10.19)
'do not commit adultery, do not kill, do not steal, do not speak false testimony'

Other meanings of the 'future imperative' 

Some verbs have only the second imperative, for example  'know',  'remember'. In this case the imperative often has a present rather than future meaning:

 (Cicero)
'know that I have been blessed with a little son, and that Terentia is safe'

In theory there is also a future passive imperative, but it is extremely rare. It can be is either 2nd or 3rd person:

 (Ausonius)
'A spouse should be joined equal to equal' (or: 'Be joined as a spouse equal to an equal')

3rd person formal imperative
Related to the colloquial future imperative is the formal imperative (usually used in the 3rd person) of legal language, as in this invented law from Cicero's :

 (Cicero)
'there shall be two men with royal power; and since they consult [us] we shall call them 'consuls'; they should obey nobody; for them the welfare of the people shall be the supreme law'

According to J.G.F. Powell,  is not a genuine archaic form; in early Latin  is used only in deponent verbs and is 2nd or 3rd person singular. Meminī, ōdī, nōvī

The future perfect and pluperfect of these verbs serve as the equivalent of a future or imperfect tense:  'I will remember',  'I remembered'. has an imperative  'remember!' There is also a subjunctive which can be used in a hortatory sense:

 (Petronius)
'let us remember the living (not the dead)!' Secondary tense

A task can be temporally placed relative to a future event, in which case it is to be carried out before, during or after that event. In such cases, it is realised by 'future imperative' verbs. This mode of representing tasks is very frequent in text by early writers (Plautus and Cato) and sporadically found in texts by later authors (Cicero and Martial):

References

Latin grammar
Grammatical tenses