String replacement (${var/old/new}) in Bash Scripting - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this string replacement?

Given the following bash script, what will be printed?

Bash Scripting

text="hello world"
echo ${text/world/universe}

A hello universe

B hello world

C universe world

D hello

💡 Hint

The syntax ${var/old/new} replaces the first occurrence of 'old' with 'new' in the variable's value.

The variable 'text' contains 'hello world'. The expression ${text/world/universe} replaces the first 'world' with 'universe', so the output is 'hello universe'.

💻 Command Output

intermediate

What does this double slash replacement output?

What will this bash command output? text="banana bandana" echo ${text//ana/123}

Bash Scripting

text="banana bandana"
echo ${text//ana/123}

A b123 b123d123

B b123na band123

C banana bandana

D b123na b123d123

💡 Hint

Using double slashes replaces all occurrences, not just the first.

The expression ${text//ana/123} replaces all 'ana' substrings with '123'. So 'banana' becomes 'b123na' and 'bandana' becomes 'band123'.

💻 Command Output

advanced

What is the output when replacing a substring that does not exist?

Consider this bash code: text="apple orange" echo ${text/applee/fruit}

Bash Scripting

text="apple orange"
echo ${text/applee/fruit}

A Syntax error

B fruit orange

C orange

D apple orange

💡 Hint

If the substring to replace is not found, the original string remains unchanged.

Since 'applee' is not found in 'apple orange', no replacement occurs, so the output is the original string.

💻 Command Output

advanced

What is the output of this nested replacement?

What will this bash script print? text="foo bar foo" echo ${text/foo/bar} echo ${text//foo/bar}

Bash Scripting

text="foo bar foo"
echo ${text/foo/bar}
echo ${text//foo/bar}

A

bar bar foo
bar bar bar

B

bar bar foo
foo bar foo

C

foo bar foo
bar bar bar

D

bar bar foo
bar foo bar

💡 Hint

Single slash replaces first occurrence; double slash replaces all occurrences.

The first echo replaces only the first 'foo' with 'bar', resulting in 'bar bar foo'. The second echo replaces all 'foo' with 'bar', resulting in 'bar bar bar'.

💻 Command Output

expert

What is the output when using replacement with special characters?

Given this bash code, what will be the output? text="path/to/file.txt" echo ${text//./_}

Bash Scripting

text="path/to/file.txt"
echo ${text//./_}

A txt_elif/ot/htap

B path/to/file_txt_

C path/to/file_txt

D ath/to/file_txt

💡 Hint

The dot '.' is replaced by underscore '_' everywhere in the string.

The expression replaces all '.' characters with '_'. Since there is only one dot before 'txt', it becomes 'path/to/file_txt'.