Perl Substitution g Modifier

The global modifier (g) makes the replacement happen on all occurrences of the matched pattern.
For example, this will replace only the first occurrence of the with el:

s/the/el/

Perl modifiers (flags)*

Modifier	Description
a	Match \d, \s, \w and POSIX in ASCII range only
c	Keep current position after match fails
d	Use default, native rules of the platform
g	Global matching
i	Case-insensitive matching
l	Use current localeï¿½s rules
m	Multiline strings
p	Preserve the matched string
s	Treat strings as a single line
u	Use Unicode rules when matching
x	Ignore whitespace and comments

But this will replace all occurrences:

s/the/el/g