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bash internal / data manipulations (105)

Feature Group

bash internal / data manipulations (105)

bash

This demonstrates prefix name expansion in Bash to list all variables that start with a specified prefix.


prefix_a=one
prefix_b=two
echo ${!prefix_*}  # all variables names starting with `prefix_`
# => prefix_a prefix_b

bash internal data manipulations string manipulation and expansions parameter expansion prefix expansion

bash

This demonstrates converting the first character of a variable to lowercase using parameter expansion.


${Var,}

bash internal data manipulations string manipulation and expansions parameter expansion string case conversion

bash

This demonstrates capitalizing the first letter of a string using parameter expansion.


${Var^}

bash internal data manipulations string manipulation and expansions parameter expansion case modification

bash

This demonstrates case conversion using parameter expansion in Bash.


str="HELLO WORLD!"
echo "${str,}"   #=> "hELLO WORLD!" (lowercase 1st letter)
echo "${str,,}"  #=> "hello world!" (all lowercase)

str="hello world!"
echo "${str^}"   #=> "Hello world!" (uppercase 1st letter)
echo "${str^^}"  #=> "HELLO WORLD!" (all uppercase)

bash internal data manipulations string manipulation and expansions parameter expansion case conversion

bash

This demonstrates conditional value substitution using parameter expansion in Bash.


${foo:+val}

bash internal data manipulations string manipulation and expansions parameter expansion conditional substitution

bash

This demonstrates providing a default value for a variable if it is unset or null.


${foo:-val}

bash internal data manipulations string manipulation and expansions parameter expansion default value substitution

bash

This demonstrates accessing the first argument passed to a script or function.

$1

bash internal data manipulations positional arguments positional argument

bash

This demonstrates the use of $@ to handle all positional parameters passed to a script or function in Bash.

$@

bash internal data manipulations positional arguments positional argument

bash

This demonstrates various operations on an array in Bash, including accessing elements, counting elements, slicing, and listing indices.


echo "${Fruits[0]}"           # Element #0
echo "${Fruits[-1]}"          # Last element
echo "${Fruits[@]}"           # All elements, space-separated
echo "${#Fruits[@]}"          # Number of elements
echo "${#Fruits}"             # String length of the 1st element
echo "${#Fruits[3]}"          # String length of the Nth element
echo "${Fruits[@]:3:2}"       # Range (from position 3, length 2)
echo "${!Fruits[@]}"          # Keys of all elements, space-separated

bash internal data manipulations array manipulations array operations

bash

This demonstrates referencing a range of arguments from the previous command using Bash history expansion.


!!:n-$

bash internal data manipulations history features history expansion argument range

bash

This demonstrates using brace expansion to generate a list of .csv and .tsv files in the current directory.


{*.csv *.tsv}

bash internal data manipulations string manipulation and expansions brace expansion file type matching

bash

This demonstrates capturing user input from standard input and storing it in a variable.


read foo

bash internal data manipulations other variable features variable assignment

bash

This demonstrates the use of a default value in Bash using parameter expansion.


echo ${foo:-'default'}

bash internal data manipulations string manipulation and expansions parameter expansion default value substitution

bash

This demonstrates the difference between double and single quotes in Bash for variable expansion, emphasizing the importance of correct quoting practices.


echo "$variable" # => Some string
echo '$variable' # => $variable
# When you use a variable itself — assign it, export it, or else — you write
# its name without $. If you want to use the variable's value, you should use $.
# Note that ' (single quote) won't expand the variables!
# You can write variable without surrounding quotes but it's not recommended.

bash internal data manipulations string manipulation and expansions variable expansion

bash

This demonstrates setting an environment variable in Bash using the export command.


export FOO=Bar

bash internal data manipulations variable definition and usage environment variable

bash

This demonstrates escaping single and double quotes in a Bash string.


echo ''Text with single quote\'. Text with double quote\"''

bash internal data manipulations string manipulation and expansions string escaping

bash

This demonstrates substring extraction from a variable using parameter expansion.


length=7
echo "${variable:0:length}" # => Some st
# This will return only the first 7 characters of the value
echo "${variable: -5}" # => tring
# This will return the last 5 characters (note the space before -5).
# The space before minus is mandatory here.

bash internal data manipulations string manipulation and expansions parameter expansion string slicing

bash

This demonstrates indirect variable expansion in Bash, where the value of a variable is used to access another variable's value dynamically.


other_variable="variable"
echo ${!other_variable} # => Some string
# This will expand the value of `other_variable`.

bash internal data manipulations other variable features indirect variable expansion

bash

This demonstrates file extension extraction and manipulation using parameter expansion.


file="Some/path/to/file.txt"
echo "Extension: ${file##*.}"
echo "Name sans extension: ${file%.*}"
echo "New extension: ${file%txt}gif"

bash internal data manipulations string manipulation and expansions parameter expansion path manipulation

100

bash

This demonstrates printing the current Bash version using the built-in variable $BASH_VERSION.


echo "Bash version: $BASH_VERSION"

bash internal data manipulations other variable features built-in variable access

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bash

This demonstrates prefix name expansion in Bash to list all variables that start with a specified prefix.


prefix_a=one
prefix_b=two
echo ${!prefix_*}  # all variables names starting with `prefix_`
# => prefix_a prefix_b

bash internal data manipulations string manipulation and expansions parameter expansion prefix expansion

bash

This demonstrates converting the first character of a variable to lowercase using parameter expansion.


${Var,}

bash internal data manipulations string manipulation and expansions parameter expansion string case conversion

bash

This demonstrates capitalizing the first letter of a string using parameter expansion.


${Var^}

bash internal data manipulations string manipulation and expansions parameter expansion case modification

bash

This demonstrates case conversion using parameter expansion in Bash.


str="HELLO WORLD!"
echo "${str,}"   #=> "hELLO WORLD!" (lowercase 1st letter)
echo "${str,,}"  #=> "hello world!" (all lowercase)

str="hello world!"
echo "${str^}"   #=> "Hello world!" (uppercase 1st letter)
echo "${str^^}"  #=> "HELLO WORLD!" (all uppercase)

bash internal data manipulations string manipulation and expansions parameter expansion case conversion

bash

This demonstrates conditional value substitution using parameter expansion in Bash.


${foo:+val}

bash internal data manipulations string manipulation and expansions parameter expansion conditional substitution

bash

This demonstrates providing a default value for a variable if it is unset or null.


${foo:-val}

bash internal data manipulations string manipulation and expansions parameter expansion default value substitution

bash

This demonstrates accessing the first argument passed to a script or function.

$1

bash internal data manipulations positional arguments positional argument

bash

This demonstrates the use of $@ to handle all positional parameters passed to a script or function in Bash.

$@

bash internal data manipulations positional arguments positional argument

bash

This demonstrates various operations on an array in Bash, including accessing elements, counting elements, slicing, and listing indices.


echo "${Fruits[0]}"           # Element #0
echo "${Fruits[-1]}"          # Last element
echo "${Fruits[@]}"           # All elements, space-separated
echo "${#Fruits[@]}"          # Number of elements
echo "${#Fruits}"             # String length of the 1st element
echo "${#Fruits[3]}"          # String length of the Nth element
echo "${Fruits[@]:3:2}"       # Range (from position 3, length 2)
echo "${!Fruits[@]}"          # Keys of all elements, space-separated

bash internal data manipulations array manipulations array operations

bash

This demonstrates referencing a range of arguments from the previous command using Bash history expansion.


!!:n-$

bash internal data manipulations history features history expansion argument range

bash

This demonstrates using brace expansion to generate a list of .csv and .tsv files in the current directory.


{*.csv *.tsv}

bash internal data manipulations string manipulation and expansions brace expansion file type matching

bash

This demonstrates capturing user input from standard input and storing it in a variable.


read foo

bash internal data manipulations other variable features variable assignment

bash

This demonstrates the use of a default value in Bash using parameter expansion.


echo ${foo:-'default'}

bash internal data manipulations string manipulation and expansions parameter expansion default value substitution

bash

This demonstrates the difference between double and single quotes in Bash for variable expansion, emphasizing the importance of correct quoting practices.


echo "$variable" # => Some string
echo '$variable' # => $variable
# When you use a variable itself — assign it, export it, or else — you write
# its name without $. If you want to use the variable's value, you should use $.
# Note that ' (single quote) won't expand the variables!
# You can write variable without surrounding quotes but it's not recommended.

bash internal data manipulations string manipulation and expansions variable expansion

bash

This demonstrates setting an environment variable in Bash using the export command.


export FOO=Bar

bash internal data manipulations variable definition and usage environment variable

bash

This demonstrates escaping single and double quotes in a Bash string.


echo ''Text with single quote\'. Text with double quote\"''

bash internal data manipulations string manipulation and expansions string escaping

bash

This demonstrates substring extraction from a variable using parameter expansion.


length=7
echo "${variable:0:length}" # => Some st
# This will return only the first 7 characters of the value
echo "${variable: -5}" # => tring
# This will return the last 5 characters (note the space before -5).
# The space before minus is mandatory here.

bash internal data manipulations string manipulation and expansions parameter expansion string slicing

bash

This demonstrates indirect variable expansion in Bash, where the value of a variable is used to access another variable's value dynamically.


other_variable="variable"
echo ${!other_variable} # => Some string
# This will expand the value of `other_variable`.

bash internal data manipulations other variable features indirect variable expansion

bash

This demonstrates file extension extraction and manipulation using parameter expansion.


file="Some/path/to/file.txt"
echo "Extension: ${file##*.}"
echo "Name sans extension: ${file%.*}"
echo "New extension: ${file%txt}gif"

bash internal data manipulations string manipulation and expansions parameter expansion path manipulation

100

bash

This demonstrates printing the current Bash version using the built-in variable $BASH_VERSION.


echo "Bash version: $BASH_VERSION"

bash internal data manipulations other variable features built-in variable access

Previous 1

...

4 5 6 Next