Return values (return and echo) in Bash Scripting - Step-by-Step Execution

Concept Flow - Return values (return and echo)

Start function

↓

Execute commands

↓

Use echo to output value

↓

Use return to set exit status

↓

Function ends

↓

Caller captures echo output or return status

↓

Use output or status in script

A bash function uses echo to send output text and return to set an exit status code. The caller can capture either.

Execution Sample

Bash Scripting

myfunc() {
  echo "Hello"
  return 3
}
myfunc
status=$?
output=$(myfunc)

Defines a function that echoes text and returns a status; then calls it capturing both.

Execution Table

Step	Action	Echo Output	Return Status	Notes
1	Call myfunc			Function starts
2	Execute echo "Hello"	Hello		Output sent to stdout
3	Execute return 3		3	Function exits with status 3
4	Capture $? after myfunc		3	Return status stored in status
5	Capture output=$(myfunc)	Hello	0	Output captured, return status of subshell is 0
6	Check status variable		3	Status from first call remains 3

💡 Function ends after return; caller captures output and status separately

Variable Tracker

Variable	Start	After Call 1	After Call 2	Final
status	unset	3	3	3
output	unset	unset	Hello	Hello

Key Moments - 2 Insights

Why does the return status after capturing output with $(myfunc) show 0 instead of 3?

Because $(myfunc) runs the function in a subshell, the return status of the subshell is 0 if the command succeeds, not the function's return value. See execution_table row 5.

Can echo send a return status code?

No, echo only sends text output. The return command sets the exit status code. See execution_table rows 2 and 3.

Visual Quiz - 3 Questions

Look at the execution table, what is the value of 'status' after the first call to myfunc?

A 3

B 0

C Hello

D unset

💡 Hint

Check execution_table row 4 where status is set after myfunc returns

At which step does the function output 'Hello' to stdout?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look at execution_table row 2 for echo output

If we remove the return statement, what will be the return status after calling myfunc?

A 3

B 1

C 0

D Undefined

💡 Hint

By default, bash functions return 0 if no explicit return is given

Concept Snapshot

Bash functions use echo to send output text.
Use return to set an exit status (0-255).
Caller captures output with $(func) and status with $?.
Echo output and return status are separate.
Return ends function immediately.
Subshells affect return status capture.

Full Transcript

In bash scripting, functions can send output using echo and set an exit status using return. When you call a function, echo sends text to standard output, which you can capture using command substitution like output=$(myfunc). The return command sets a numeric exit status accessible via $?. Note that capturing output with $(myfunc) runs the function in a subshell, so the return status of the subshell is usually 0 if the command succeeds, not the function's return value. To get the function's return status, call it normally and check $?. Echo and return serve different purposes: echo for output, return for status. The function ends immediately after return. Understanding these helps you handle function outputs and statuses correctly in bash scripts.