sed

Edit text in a scriptable manner. More information: https://ss64.com/osx/sed.html.

Replace the first occurrence of a string in a file, and print the result:

sed 's/{{find}}/{{replace}}/' {{filename}}

Replace all occurrences of an extended regular expression in a file:

sed -E 's/{{regular_expression}}/{{replace}}/g' {{filename}}

Replace all occurrences of a string [i]n a file, overwriting the file (i.e. in-place):

sed -i '' 's/{{find}}/{{replace}}/g' {{filename}}

Replace only on lines matching the line pattern:

sed '/{{line_pattern}}/s/{{find}}/{{replace}}/' {{filename}}

Print only text between n-th line till the next empty line:

sed -n '{{line_number}},/^$/p' {{filename}}

Apply multiple find-replace expressions to a file:

sed -e 's/{{find}}/{{replace}}/' -e 's/{{find}}/{{replace}}/' {{filename}}

Replace separator / by any other character not used in the find or replace patterns, e.g. #:

sed 's#{{find}}#{{replace}}#' {{filename}}

[d]elete the line at the specific line number [i]n a file, overwriting the file:

sed -i '' '{{line_number}}d' {{filename}}