SHORT SED intro

sed -i 's/sadness/happiness/g' sedfile

Getting there ... ✊ ✊

Me: What did you teach me about sed yesterday?

GPT: Yesterday, I taught you about the sed command, which is a powerful text editor that can perform find and replace operations on text files.

Here is a brief summary of what we covered:

sed stands for "stream editor", and is used to modify text files by performing search and replace operations on them. The basic syntax of the sed command is:

sed 's/sadness/happiness/g' input_file>output_file

where:

• old_text is the string you want to replace

• new_text is the replacement string

• g is the "global" flag that replaces all occurrences of the string

• input_file is the file you want to edit,

• and output_file is the file where the edited text will be saved.

Note: The / acts as a separator with sed, just as [ - space] acts as a separator in bash. You can use any character you want as a separator, as long as it is not used in the strings you are searching for or replacing.

You can use regular expressions in sed to perform more complex search and replace operations, such as replacing a string only if it appears at the beginning of a line, or replacing a string only if it is surrounded by certain characters. Regular expressions are a powerful tool for working with text, and they can be used in many other programming languages and tools as well.

You can use sed to edit a file in place, without creating a new file, by using the -i option, like this:

sed -i.bak 's/sadness/happiness/g' input_file

This will edit input_file in place, creating a backup file with the extension .bak. It's important to make a backup of the original file before using the -i option, in case something goes wrong.

You can also use sed to delete lines from a file, using the d command, like this:

sed '/pattern/d' input_file > output_file

This will delete all lines that contain the specified pattern from input_file, and save the edited text to output_file.

You can insert or append text to a file using the i or a commands, respectively. For example:

sed '/pattern/i\new_text' input_file >output_file

This will insert new_text above the first line that contains pattern in input_file, and save the edited text to output_file.

sed '/pattern/a\new_text' input_file >output_file

This will append new_text below the last line that contains pattern in input_file, and save the edited text to output_file.

Overall, sed is a powerful tool for editing text files, and can save you a lot of time and effort when making changes to large or complex files. By mastering the basic syntax and learning how to use regular expressions, you can become a more efficient and effective text editor.

Learn More

• Sed - An Introduction and Tutorial by Bruce Barnett

• sed-documentation