Table of Contents
String Processing
Document some ways that Bash handles strings.
Replacement
| Command/Syntax | Description |
|---|---|
| sed 's/regexp/replacement/' | Replace the first matched pattern. |
| sed 's/regexp/replacement/g' | Replace all matched patterns. |
| ${Variable/regexp/replacement} | Replace the first matched pattern. |
| ${Variable//regexp/replacement} | Replace all matched patterns. |
Deletion
| Command/Syntax | Description |
|---|---|
| ${Variable%pattern} | Remove trailing matched pattern. |
| ${Variable#pattern} | Remove matched pattern from the head. |
Insertion
Addend 1
The line-number can also use the following special character:
$- The last line.
Demo
Insert new line 0 before line 2.
cat test
line 1
line 2
line 3
sed -i "2i new line 0" test
cat test
line 1
new line 0
line 2
line 3
Insert new line 1 before the last line.
cat test
line 1
line 2
line 3
sed -i "\$i new line 1" test
cat test
line 1
line 2
new line 1
line 3