Je vais sauvegarder le fichier avant d’éteindre l’ordinateur.

Je vais sauvegarder is the near future (futur proche): aller + infinitive.

It is very common in spoken and everyday French and often suggests something the speaker is about to do or intends to do soon.

So:

• Je vais sauvegarder le fichier = I’m going to save the file
• Je sauvegarderai le fichier = I will save the file

Both are correct, but je vais sauvegarder often sounds a bit more immediate and conversational.

They are related, but not always identical.

• sauvegarder usually means to save in the sense of protecting data, often like save or back up
• enregistrer can also mean to save, but it is broader and can also mean to record or to register

In computer contexts:

• sauvegarder un fichier = save/back up a file
• enregistrer un fichier = save a file

In many real situations, both can be used, but sauvegarder often emphasizes preserving the file safely, while enregistrer is a more general save command.

French often uses articles where English may be more flexible.

Here, le fichier and l’ordinateur are definite articles:

• le fichier = the file
• l’ordinateur = the computer

French commonly uses the definite article when the object is specific or understood from context. If you are working on a file and a computer that are already known in the situation, le and l’ sound natural.

So even if English might say save the file or sometimes just save a file, French typically wants the article.

Because after avant, when the next verb is in the infinitive, French uses de:

• avant de + infinitive

So:

• avant d’éteindre = before turning off
• avant de partir = before leaving
• avant de manger = before eating

You cannot normally say avant éteindre in standard French.

That is elision.

The preposition de becomes d’ before a word beginning with a vowel or silent h:

• de éteindre → d’éteindre
• de acheter → d’acheter
• de habiter → d’habiter (if the h is silent)

So avant de éteindre is not used; it becomes avant d’éteindre.

For the same reason: elision.

The masculine singular article le becomes l’ before a vowel or silent h:

• le ordinateur → l’ordinateur
• le ami → l’ami

So:

• le fichier
• l’ordinateur

This is required in standard French.

Because after avant de, French uses the infinitive when the subject is the same.

Here, the subject is je for both actions:

• Je vais sauvegarder...
• Je vais éteindre...

Since the same person is doing both things, French says:

• avant d’éteindre l’ordinateur

This is like saying before turning off the computer.

No. If the subject changes, French usually uses avant que + subjunctive.

Compare:

• Je vais sauvegarder le fichier avant d’éteindre l’ordinateur.
  Same subject: I will save it and I will turn off the computer.

But:

• Je vais sauvegarder le fichier avant que tu n’éteignes l’ordinateur.
  Different subject: I will save the file before you turn off the computer.

So:

• avant de + infinitive = same subject
• avant que + subjunctive = different subject

Yes. Éteindre means to switch off / turn off something powered.

Examples:

• éteindre la lumière = turn off the light
• éteindre la télévision = turn off the TV
• éteindre l’ordinateur = turn off the computer

It refers to powering it down, not merely closing something.

They are not the same.

• éteindre l’ordinateur = turn off/shut down the computer
• fermer l’ordinateur = literally close the computer

For a laptop, fermer l’ordinateur could mean physically closing the lid, not shutting the system down.

Also:

• fermer un fichier / une fenêtre / un programme = close a file / window / program
• éteindre is for switching power off

So in this sentence, éteindre is the correct choice if the meaning is turn off.

Yes.

• avant le dîner = before dinner
• avant la réunion = before the meeting

But if a verb follows, you usually need:

• avant de + infinitive
  or
• avant que + subjunctive

So in this sentence, because a verb follows, avant d’éteindre is the correct structure.

Sauvegarder is a regular -er verb, but in this sentence you do not conjugate it because it comes after vais in the aller + infinitive structure.

So:

• je vais sauvegarder
• not je vais sauvegarde

Only aller is conjugated here:

• je vais
• tu vas
• il/elle va
• nous allons
• vous allez
• ils/elles vont

Then the second verb stays in the infinitive:

• sauvegarder

A more formal or slightly more literary version could use the simple future:

• Je sauvegarderai le fichier avant d’éteindre l’ordinateur.

This is perfectly natural in writing.

The original sentence:

• Je vais sauvegarder le fichier avant d’éteindre l’ordinateur.

sounds very natural in everyday speech and informal writing.

So the choice is mostly about style and nuance, not right vs. wrong.