JustUtils
shield_lockLinux permissions 路 explained as you click

Chmod 755 Explained & Calculator

See exactly what chmod 755 allows, why it is common for directories and scripts, and copy a safe ready-to-use command.

STEP 1

What are you changing?

Execute means different things for a file and a directory.

For a directory: Read lists names, Write adds or removes items, and Execute lets someone enter the directory and reach items inside.

STEP 2

Choose access

Owner permissions

Owner

digit 1 路 7

rwx

Usually you or the account that created it.

Group permissions

Group

digit 2 路 5

r-x

Accounts collected in the file's owning group.

Everyone else permissions

Everyone else

digit 3 路 5

r-x

Any other account on the same system.

YOUR RESULT

755rwxr-xr-x

u=rwx,g=rx,o=rx

Owner

Can list names, add or remove items, enter

Group

Can list names, enter

Everyone else

Can list names, enter

THE PART MOST CALCULATORS SKIP

See what will actually change

Find the numeric mode with stat -c '%a' path on Linux, then review each permission being added or removed.

644arrow_forward755
addOwner: executeaddGroup: executeaddEveryone else: execute

TOP 5 EVERYDAY MODES

Start from the job, not the digits

Each common mode has its own explainer page and loads directly into this calculator. Pick the situation that sounds like yours, then check the access before copying.

folder_open755

Public directory or script

You control it; everyone else can open or run it.

description644

Regular file

You can edit it; everyone else can read it.

key600

Private or secret file

Only you can read or edit it.

lock700

Private directory or script

Only you can open, change, or run it.

group775

Team directory

You and your group can edit; everyone else can browse.

CHMOD IN ONE MINUTE

What is chmod?

Every Linux file carries a tiny access list. chmod is the command that rewrites that list. It does not move the file, change its contents, or choose its owner鈥攊t only changes what the owner, group, and everyone else are allowed to do.

Think of the three digits as three keycards. The first card belongs to the owner, the second to the group, and the third to everyone else. Each card gets points for Read (4), Write (2), and Execute (1). Add the allowed actions to get that card's digit.

The only math you need

4Read+2Write+1Execute=7all three
Why 777 is not a universal fix: it hands every keycard every permission. Fix ownership or choose the smallest access that solves the real need instead.

DIGIT 1 路 u

Owner

Usually you or the account that created it.

DIGIT 2 路 g

Group

Accounts collected in the file's owning group.

DIGIT 3 路 o

Everyone else

Any other account on the same system.

Chmod 755 in practice

How to decide whether 755 fits your directory

Mode 755 gives the owner read, write, and execute access. The group and everyone else receive read and execute access but cannot modify the item. On a directory, execute means the ability to enter it and reach items whose names are known.

Owner
7 = read + write + execute
The owning account can list, enter, create, rename, and remove items when directory rules allow.
Group
5 = read + execute
Members of the owning group can list and enter the directory but cannot add or remove entries.
Everyone else
5 = read + execute
Other local accounts receive the same browsing access as the group.

A practical example

A public website directory owned by the deploy account

A web server needs to traverse a document directory and read public files, while only the deployment account should change the directory contents. Mode 755 can provide that directory access when file modes, ownership, parent directories, and the web-server account are also configured correctly.

Before saving the change

  • Run ls -ld on the directory and confirm the intended owner and group.
  • Check files separately; ordinary public files commonly use 644 and do not need execute.
  • Test access as the service account before applying the mode recursively.

Common mistake to avoid

Using chmod -R 755 on a mixed website tree marks ordinary files executable. It also replaces intentional private or group-writable permissions inside the tree.

When to choose something else

Choose 750 when only the owner and group should enter the directory. Choose 775 when a correctly configured group genuinely needs to create and edit items.