In addition to editors like emacs, you can also edit files directly from the terminal using sed, the built-in stream editor. You can use it to make substitutions or deletions in a file with commands such as:
sed 's/oldword/newword/g' filename
which substitutes “newword” for “oldword”. The “g” makes the substitution global (all instances on that line). Without the g, it will only change the first match on that line.
Other sed commands:
sed 's/word/d' filename
This deletes the whole line, not just the word. To delete just the word:
sed 's/word//' filename
The examples given will print out the changes to the terminal. If you want to print the changes to a file instead type:
sed 's/oldword/newword/' filename > newfilename where > directs the output into a file called newfilename
To link more than one command together use &&. For example:
sed 's/oldword/newword/' filename > newfilename && emacs newfilename

	sed ‘s/string1/string2/g’	Replace string1 with string2
	sed ‘s/\(.*\)1/\12/g’	Modify anystring1 to anystring2
	sed ‘/ *#/d; /^ *$/d’	Remove comments and blank lines
	sed ‘:a; /\\$/N; s/\\\n//; ta’	Concatenate lines with trailing \
	sed ‘s/[ \t]*$//’	Remove trailing spaces from lines
	sed ‘s/\([\\`\\”$\\\\]\)/\\\1/g’	Escape shell metacharacters active within double quotes
•	seq 10 | sed “s/^/      /; s/ *\(.\{7,\}\)/\1/”	Right align numbers
	sed -n ‘1000p;1000q‘	Print 1000th line
	sed -n ‘10,20p;20q‘	Print lines 10 to 20
	sed -n ‘s/.*<title>\(.*\)<\/title>.*/\1/ip;T;q‘	Extract title from HTML web page
	sort -t. -k1,1n -k2,2n -k3,3n -k4,4n	Sort IPV4 ip addresses
•	echo ‘Test’ | tr ‘[:lower:]’ ‘[:upper:]’	Case conversion
•	tr -dc ‘[:print:]’ < /dev/urandom	Filter non printable characters
•	history | wc -l	Count lines