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| command | meaning |
|---|---|
| ${parameter:-defaultValue} | Get default shell variables value |
| ${parameter:=defaultValue} | Set default shell variables value |
| ${parameter:?"Error Message"} | Display an error message if parameter is not set |
| ${#var} | Find the length of the string |
| ${var%pattern} | Remove from shortest rear (end) pattern |
| ${var%%pattern} | Remove from longest rear (end) pattern |
| ${var:num1:num2} | Substring |
| ${var#pattern} | Remove from shortest front pattern |
| ${var##pattern} | Remove from longest front pattern |
| ${var/pattern/string} | Find and replace (only replace first occurrence) |
| ${var//pattern/string} | Find and replace all occurrences |
| ${!prefix*} | Expands to the names of variables whose names begin with prefix. |
| ${var,} | Convert first character to lowercase. |
| ${var,pattern} | Convert only if the pattern match |
| ${var,,} | Convert all characters to lowercase. |
| ${var,,pattern} | Convert only if the pattern match |
| ${var^} | Convert first character to uppercase. |
| ${var^pattern} | Convert only if pattern match |
| ${var^^} | Convert all character to uppercase.} |
| ${var^^pattern} | Convert only if pattern match |
