# Container
A container is one of the following items: 

large box
chest
ice box
sack
oilskin sack
bag of holding
Each can store an unlimited number of items (objects or money), but may become too heavy to lift as a consequence. For a container that's in your inventory, you can access its contents with the apply command. If the container is on the ground, you can do the same by using the #loot command. 
Even though the bag of tricks is defined with the `CONTAINER` macro in objects.c (and an unidentified one appears as a "bag", like three other containers), it cannot actually store items in vanilla NetHack.
A statue can also function as a container; this causes messages like, "The statue of the Foo is empty."[1] The contents correspond to the inventory of that monster before it was stoned. Some statues are generated with spellbooks inside.
The floor and ice are also technically containers, and can store buried items (e.g. under a randomly generated headstone). These items can be accessed by digging a pit.

Contents

1 General properties
2 Containers within containers
3 Generation
4 Unlocking

4.1 Messages

5 Breakable items
6 History
7 Variants

7.1 Iron safe
7.2 Magic chest
7.3 FIQHack

8 References

General properties
As long as a container is not destroyed or polymorphed, all its contents stay unchanged, protected from any magical or physical influence, with four exceptions:

Aging: Only an ice box preserves eggs and corpses from (further) aging; in other containers they rot as usual. Furthermore, troll corpses in containers can still resurrect, unless the container is locked.
Wetting: If you get into or under the water without wearing an oilskin cloak, only a non-cursed oilskin sack, a chest, an ice box, or a large box completely protects its contents from the water damage.
Breaking: If a container is kicked, thrown, or dropped from height, fragile objects in it may break. A bag of holding is a magical container, and will protect its fragile contents from damage.
Vanishing: When opening a cursed bag of holding, each item inside has a chance of vanishing.
In particular, containers completely protect their contents from fire, cold, shock, cancellation, being stolen or picked up by monsters, being identified, and changing their BUC. There is no monster in the game that can access containers' contents (but see below for gelatinous cubes).
When you carry a container, its contents do not take up slots (letters) in your inventory. Therefore, you can normally carry only 52 object stacks in your main inventory, but with a container, you can carry an unlimited number of objects.
If a container is trapped, opening it manually will trigger the trap.
The unique items cannot be placed into containers. A cheap plastic imitation of the Amulet of Yendor can, however; this is commonly used to distinguish the real Amulet from fake ones.
All of the containers except ice boxes can be eaten by gelatinous cubes; the contents will be engulfed. but unharmed, and can be found on the cube's corpse once killed. If you are polymorphed into a gelatinous cube, you can eat these containers only if they are empty.
When a container is polymorphed (even to another container, or even to the same container), all of its contents are destroyed.

The following information pertains to an upcoming version (NetHack 3.7.0). If this version is now released, please verify that it is still accurate, then update the page to incorporate this information.

Monsters now pick up containers and can loot containers other than a cursed bag of holding. As of yet, monsters cannot open locked containers.
Containers within containers
Generally, containers may contain other containers. However, there are exceptions.

Large boxes, ice boxes, and chests are too big to fit into any other container.
If you put a bag of holding, charged bag of tricks, or charged wand of cancellation into a bag of holding, the bag will explode, destroying all its contents including the item that caused the explosion.
Attempting to place a container into itself yields the message "That would be an interesting topological exercise."

Generation
Containers created via normal generation (i.e. outside of bones files or trap "bones") are uncursed, with the contents as described below:
Containers will not be generated containing tools, weapons, armor, or rocks. Containers in your starting inventory will be empty.
If the container can be locked, then there is an 80% chance that it will be generated locked and, independently, a 10% chance that it will be trapped.

Container

Contents

Lockable

Probability

sack

0–1 items

No

3.5%

large box

0–3 items

Yes

4.0%

chest

0–5 items

Yes

3.5%

ice box

0–20 corpses

No

0.5%

bag of holding

0–1 items

No

2.0%

bag of tricks

1–20 charges

No

2.0%

oilskin sack

0–1 items

No

0.5%

Tools can be generated in the main dungeon (8% of all objects) and Gehennom (12% of all objects). Each tool has the given probability of being a container.
Large boxes and chests with contents may generate within some rooms in an ordinary room-and-corridor level.[2]  Large boxes are twice as common as chests.  A comment in the source cites a 40% chance of at least one container (with a low probability of extra ones); the actual chance is slightly lower and depends on the number of rooms and presence of a special room; a good estimate is 34% without a special room and 30% with one.  
Quantum mechanics may carry a large box containing a housecat named Schroedinger's Cat.
Items generated in a container (other than an ice box) will each be one of the following types:

Type

Probability

gem or stone

18%

comestible

15%

potion

18%

scroll

18%

spellbook

12%

gold

7%

wand

6%

ring

5%

amulet

1%

Weapons, armor, and tools (including other containers) will never be generated in a container. Gold generated in containers will be 2.5 times the usual amount. Gemstones, glass, luckstones, and loadstones can all be generated, but flint stones, touchstones, and rocks cannot. A wand of cancellation will never be generated in a bag of holding.

Unlocking
To unlock a locked container, you can:

Apply an unlocking tool to it.
Zap a wand of opening at it.
Kick it. Because this often destroys fragile items inside, it's not the best method.
Cast the knock spell at it
Force the lock with your currently-wielded weapon. Using a blunt weapon (such as a war hammer, staff, or mace) exercises strength but risks destroying the container or its contents. Using a sharp weapon (such as a dagger, sword, or axe) exercises dexterity but risks destroying the weapon. Artifact weapons are much less likely to break.  Cursed weapons will never break, preventing locks from being used to get rid of them.
Usually, you will find enough disposable uncursed orcish daggers to force with until you get an unlocking tool. If no other options are available, you could use a junk&nbsp;artifact such as Sting, but chest contents in the early game aren't usually worth risking a good weapon or creating Sting.

Messages
You succeed in unlocking the 

<container>.
You successfully applied an unlocking tool.
Klick!
You unlocked it magically, with either the spell of knock or a wand of opening.
THUD!
You kicked it and didn't open it.
THUD! The lid slams open, then falls shut.
It wasn't locked, and you kicked it open.
You break open the lock!
It was locked, and you kicked the lid open.
You hear a muffled shatter.
You kicked it, and at least one breakable item inside was destroyed.
You hear a muffled cracking.
You kicked it, and at least one egg inside was destroyed.
Breakable items
If a container is kicked, thrown, or dropped from a height, contents which are fragile (such as potions, mirrors, and eggs) may be destroyed.
When glass objects in a bag, large box, or chest break, you hear a muffled shatter. An egg gives a muffled cracking when it breaks. You will lose that object and will not know what it was.
If a mirror in a box is destroyed through your actions, you will still incur a Luck penalty. However, mirrors and other tools are never randomly generated inside boxes.

History
Prior to NetHack 3.2.0, a popular technique for identifying worthless glass was called "kickboxing". One would gather a large pile of gems, name all of them "fake red" or whatever color, dump them in a box, and then repeatedly kick the box until no more muffled shatters were heard. One would then retrieve the remaining gems and un-name them. In this way, glass of all colors could be identified. Starting with NetHack 3.2.0, worthless glass no longer breaks, so kickboxing no longer works.

Variants
Iron safe
This is a container added to SporkHack (and later to UnNetHack and then EvilHack). It is possible to open it using a wand of opening, knock spell, or stethoscope. The only way to lock an iron safe after it's been opened is to use either a wand of locking or the wizard lock spell on it.

Magic chest
In DynaHack, magic chests are dungeon features (not items) that are generated at fixed places in the dungeon. They share their contents, so putting items in any magic chest makes them available for looting in all other magic chest locations.[3] (See below for FIQHack's magic chests.)
In NetHack Fourk, magic chests have some items inside when you first open one, randomized but suited for your role.  Also, you can create a magic chest in any location by reading a scroll of consecration while confused.
In dNetHack, magic chests are items rather than dungeon features, and they have 10 slots for different compartments for those willing to categorize items. All of the compartments are shared similarly across all chests. As items, they can be wished for as long as you're not in the Planes. They're heavier than the normal theoretical max capacity, but with some of the items in dNetHack that increase it further, this can be worked around. Items in a magic chest do not add to the weight, allowing you to theoretically carry an infinite amount of items in them if you can comfortably carry a magic chest. However, you cannot open them from the inventory, so they can't make a normal bag of holding fully obsolete.

FIQHack
FIQHack has magic chests, similar to DynaHack or Nethack Fourk.  They are objects but they behave like dungeon features - they can't be picked up, teleported, polymorphed, etc.  You can create a magic chest by wishing for one.  Minetown, Sokoban, the Castle, Orcus-town, and the quest home all have magic chests.
Also note that monsters in FIQHack can use containers - they can carry items in bags and loot items from containers on the floor.  The Castle chest is special-cased to prevent monsters from stealing the guaranteed wand of wishing.

References

↑ end.c in NetHack 3.4.3, line 948

↑ src/mklev.c in NetHack 3.6.1, line 839

↑ https://github.com/tung/DynaHack/commit/b97d99ed27123fa0717ef8368b4f0d49d815c2c8

This page may need to be updated for the current version of NetHack.
It may contain text specific to NetHack 3.6.0. Information on this page may be out of date.
Editors: After reviewing this page and making necessary edits, please change the {{nethack-360}} tag to the current version's tag or {{noversion}} as appropriate.

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