Debugging with PS4 in Bash Scripting - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to enable debugging output with PS4.

Bash Scripting

export PS4=[1]
set -x
ls
set +x

Drag options to blanks, or click blank then click option'

A"+ $BASH_SOURCE:$LINENO:"

B"- $BASH_SOURCE:$LINENO:"

C"$BASH_SOURCE-$LINENO>"

D"$LINENO:$BASH_SOURCE>"

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect variable names in PS4.

Not quoting the PS4 value properly.

Setting PS4 to "+ $BASH_SOURCE:$LINENO:" shows the script name and line number before each command when debugging is enabled.

2fill in blank

medium

Complete the code to print the current function name in PS4 during debugging.

Bash Scripting

export PS4='+ $BASH_SOURCE:$LINENO:$[1]: '
set -x
myfunc() {
  echo "Hello"
}
myfunc
set +x

Drag options to blanks, or click blank then click option'

AFUNCNAME[0]

BFUNCNAME()

CFUNCNAME

DFUNCNAME[1]

Attempts:

3 left

💡 Hint

Common Mistakes

Using FUNCNAME without index which prints the whole array.

Using FUNCNAME[0] which is the current function, not the caller.

FUNCNAME[1] gives the name of the current function being executed, useful in PS4 for debugging function calls.

3fill in blank

hard

Fix the error in the PS4 assignment to correctly show timestamp and line number.

Bash Scripting

export PS4='$(date +"%T") [1] $LINENO: '
set -x
ls
set +x

Drag options to blanks, or click blank then click option'

A"+"

B"-"

C"|"

D"=>"

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' which can be confused with options.

Using symbols that clutter the debug output.

Using '+' as a separator in PS4 is common and clear; it separates the timestamp and line number nicely.

4fill in blank

hard

Fill both blanks to create a PS4 that shows script name and function call depth.

Bash Scripting

export PS4='+ $[1]:$[2]> '
set -x
func() {
  echo "Test"
}
func
set +x

Drag options to blanks, or click blank then click option'

ABASH_SOURCE

BFUNCNAME

CLINENO

DBASH_LINENO

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing LINENO with function name.

Using BASH_LINENO which shows line numbers of functions, not names.

BASH_SOURCE shows the script name; FUNCNAME shows the function call stack, useful for debugging depth.

5fill in blank

hard

Fill all three blanks to create a PS4 that shows timestamp, script name, and line number.

Bash Scripting

export PS4='[[1]] $[2]:[3]: '
set -x
ls
set +x

Drag options to blanks, or click blank then click option'

Adate +"%H:%M:%S"

BBASH_SOURCE

CLINENO

DFUNCNAME

Attempts:

3 left

💡 Hint

Common Mistakes

Using FUNCNAME instead of LINENO for line number.

Not quoting the date command properly.

This PS4 shows the current time, script name, and line number for detailed debugging info.