Case Modify

Text Case Modification In Bash

• 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).

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