← ACARA Digital Technologies Years 9–10

Reading a permission string like rwxr-x---

Three groups of three letters for owner, group and others: r is read, w is write, x is execute and - means not allowed. Here the owner has rwx, group r-x, others nothing.

Part of: ACARA Digital Technologies Years 9–10 — Networked Systems and Access Control — Module 116, WA Computer Science ATAR Year 11 — Network Communications — Module 128

Understanding Reading a permission string like rwxr-x--- in ACARA Digital Technologies Years 9–10

What it does: Each digit is r=4, w=2, x=1 added up. 7 = 4+2+1 = rwx and 5 = 4+1 = r-x, so 755 is rwxr-xr-x. 6 = 4+2 = rw- for the owner, and 4 = r-- for both group and others, so 644 is rw-r--r--. r means read, the dash in the middle means write is not allowed, and x means execute. So the group can read and run the file but not change it. In numeric form r = 4, w = 2 and x = 1. 7 = 4+2+1 = rwx, and 5 = 4+1 = r-x. So 755 is rwxr-xr-x. The string rw-r--r-- is 644.

Common mistakes: A permission string must have 9 characters (3 groups of 3). This one has only 8, so the others group is incomplete. It should be "rwxr-x---". The owner group is the first three letters, so the slice must be perm[0:3]. Slicing 0:2 misses the x/dash for execute.

Class: _____________________ · Name: _____________________ · Date: _________

Free printable worksheet with full answer key — or add this module to a class and your students practise it interactively.

🖨 Print worksheet + answer key Add Reading a permission string like rwxr-x--- to a class →

This module's key terms are also in a printable crossword (Modules 116–154) and word search (Modules 116–225).

Take this worksheet further — free with Cloodit

Each concept is reinforced from every angle — learned, then applied, then tested.

Learning

Duo

In the permission string rwxr-x---, who do the FIRST three characters (rwx) apply to?

Everyone else (others)The owner

Matches

rwxr-x--- means others can read and execute

↓

Others are the LAST group, which is ---, so they have no access. The r-x belongs to the group, not others.

Applying

Meanings

Term

rwxr-x---

Meaning

Three groups of three letters for owner, group and others: r is read, w is write, x is execute and - means not allowed. Here the owner has rwx, group r-x, others nothing.

Practice

rwxr-x--- = 750

Testing

Gaps

Owner: rwx Group: Others: ---

Check Answer

Spots

1perm = "rwxr-x--"

2owner = perm[0:3]

Cloodit turns curriculum-aligned coding content into journeys students work through one biome at a time.

Students earn collectable badges

Over 100 of them, across seven natural biomes.

Study Buddy

Students build a real study resource

Turns their work into revision material ready for Flash Cards and Exam study.

Diamond Dash — one of Cloodit's live, competitive Sprint games

Students lock in with Sprints

Live, competitive practice for the start of the lesson or a teacher-led lesson finisher.

A Cloodit certificate of achievement, ready to personalise and print

Custom printable certificates

Honour your top performers, or encourage a student who's trying hard — ready to print in seconds.

Add to class →

Quick Questions

1. In the permission string rwxr-x---, who do the FIRST three characters (rwx) apply to?

A. The owner ✓

B. Everyone else (others)

The string is split into three groups of three: owner, then group, then others. The first group, rwx, belongs to the owner.

2. What does the group part (r-x) of rwxr-x--- allow?

A. Read and execute, but not write ✓

B. Read and write, but not execute

r means read, the dash in the middle means write is not allowed, and x means execute. So the group can read and run the file but not change it.

3. In rwxr-x---, what can others (the last three characters) do?

A. Read the file only

B. Nothing, because all three are dashes ✓

The last group is ---. A dash means not allowed, so others have no read, write or execute access.

4. Which permission string means the owner can read and write, but the group and others can only read?

A. rw-r--r-- ✓

B. r--rw-r--

In rw-r--r-- the owner group is rw-, the group is r-- and others are r--. In the wrong option the write permission belongs to the group instead of the owner.

5. What does a dash (-) mean in a permission string like rw-r--r--?

A. That permission is allowed but unused

B. That permission is not allowed ✓

A dash is a blank slot. It means that r, w or x is not given to that group.

Match the Pairs

rwxr-x--- → Owner can read, write and execute; group can read and execute; others have no access.

rw-r--r-- → Owner can read and write; group and others can only read.

Numeric form 755 gives the owner full permissions and everyone else read and execute only. → 755 = rwxr-xr-x

Numeric form 644 gives the owner read and write, and everyone else read only. → 644 = rw-r--r--

rwxr-x--- means others can read and execute → Others are the LAST group, which is ---, so they have no access. The r-x belongs to the group, not others.

rw-r--r-- means the owner can only read → The first group rw- shows the owner can read and write. The dash in the third place only means no execute.

Key Term

rwxr-x---

Three groups of three letters for owner, group and others: r is read, w is write, x is execute and - means not allowed. Here the owner has rwx, group r-x, others nothing.

Fill in the Blanks

1. Permission: rwxr-x--- Owner: rwx Group: r-x Others: ---

Hint: Type the three characters that make up the middle group of the permission string.

2. r = read, w = write, x = execute

Hint: Type the single letter that allows a file to be run.

3. rwxr-xr-x is the same as 755

Hint: Type the three-digit number form. Add r=4, w=2, x=1 for each group.

4. rw-r--r-- is the same as 644

Hint: Type the three-digit number form. The owner can read and write, everyone else can only read.

5. Others have no access: rwxr-x---

Hint: Type the three characters for the last group when nothing is allowed.

Spot the Error

Question 1

A perm = "rwxr-x--"

B owner = perm[0:3]

C group = perm[3:6]

D others = perm[6:9]

Line A — A permission string must have 9 characters (3 groups of 3). This one has only 8, so the others group is incomplete. It should be "rwxr-x---".

Question 2

A perm = "rw-r--r--"

B owner = perm[0:2]

C group = perm[3:6]

D others = perm[6:9]

Line B — The owner group is the first three letters, so the slice must be perm[0:3]. Slicing 0:2 misses the x/dash for execute.

Question 3

A perm = "rwxr-xr-x"

B group = perm[6:9]

C print(group)

Line B — The group permissions are the middle three letters, perm[3:6]. perm[6:9] is the others group.

Question 4

A r = 4

B w = 2

C x = 2

D print(r + w + x)

Line C — In numeric form read is 4, write is 2 and execute is 1. Giving execute the value 2 would make 755 and 644 add up wrongly. It should be x = 1.

Question 5

A perm = "rw-r--r--"

B owner = 4 + 2

C group = 4

D others = 0

E print(owner, group, others)

Line D — The others group in rw-r--r-- is r--, which allows read only, so its number is 4. This is why the numeric form is 644. It should be others = 4.

Student with a class code? Join your class →