I realize that this is beside your point, but…don't shell out to `tr` like you did. It's really slow and Bash has built-in facilities for manipulating strings—especially case.
Equivalent to your code `input=$(echo "$value" | tr '[:upper:]' '[:lower:]')` would be something like:
input="$*"
input="${input,,}"
We are assigning a new value to the `bash` variable `input`. The right-hand-side of the `=` is the new value.
If we used `${input}`, that would just be the value already in variable `input`.
The magic is in those two commas `,,`. A `,` operator after the variable name downcases the first letter of the variable and leaves the rest of the value unchanged. The double-comma `,,` operator after the variable downcases every character in the value.
- You can use `^` and `^^` for uppercasing.
- You could have done the same in a single line with `input="${*,,}"`
I ran the `tr` version as written above 1000 times and a "pure" Bash equivalent. The `tr` version took 4.1 sec versus "pure" Bash's 0.04 sec (100 X faster).
See: https://gist.github.com/cfraizer/8f17c375837f6d904bcafd3adaa8466d for the code.
@cfraizer
I realize that this is beside your point, but…don't shell out to `tr` like you did. It's really slow and Bash has built-in facilities for manipulating strings—especially case. Equivalent to your code `input=$(echo "$value" | tr '[:upper:]' '[:lower:]')` would be something like: input="$*" input="${input,,}" We are assigning a new value to the `bash` variable `input`. The right-hand-side of the `=` is the new value. If we used `${input}`, that would just be the value already in variable `input`. The magic is in those two commas `,,`. A `,` operator after the variable name downcases the first letter of the variable and leaves the rest of the value unchanged. The double-comma `,,` operator after the variable downcases every character in the value. - You can use `^` and `^^` for uppercasing. - You could have done the same in a single line with `input="${*,,}"` I ran the `tr` version as written above 1000 times and a "pure" Bash equivalent. The `tr` version took 4.1 sec versus "pure" Bash's 0.04 sec (100 X faster). See: https://gist.github.com/cfraizer/8f17c375837f6d904bcafd3adaa8466d for the code.