String

Native String

Any unresolved token would be interpreted as string as a final fallback.

name=john_smith # it's a string without quotes

Raw String

Use single quotes to represent a raw string. All escapes are treated as literal.

script='
    cd $(ls ~/projects/* | fzf)
    echo hello
'

NOTE

You can't interpolate in single quote string

Interpolated String

Use double quotes to represent interpolated string.

first_name=john
last_name=smith
fullname="$first_name $last_name"

The best practice is using the complete ${} to distinguish between.

number=123
echo "$number456" # number123 not available in the context
echo "${name}456" # use this instead!

String Concatenation

Strings can be concatenated directly side by side except spaces.

first_name=john
last_name=smith
fullname=${first_name}${last_name}    # johnsmith #
fullname=${first_name}" "$last_name # john smith #
fullname=$first_name $last_name   # error: command not found #

Here-Doc String

Here-Doc is a convenient way to pass string from stdin to target cli. It also preserve indentation just like multi-line raw string. This feature is not specific to string itself but a syntax sugar for passing value without creating subshell.

A Here-Doc uses arbitrary delimiter to scope the string instead of quotes, the common one is EOF.

Interpolated Here-Doc

By default, a Here-Doc string can perform interpolation.

python3 << PY
import os
print("${USER}") # USER is interpolated
PY

Literal Here-Doc

Quoting first delimiter makes the Here-Doc string literally interpreted.

python3 << 'PY'
import os
print(os.environ.get("USER"))
PY