Pattern: Use of alias with definition
Issue: -
Alias expansion happens at parse time, which means to have an effect, the alias command must be executed not just before the alias is invoked, but before the invocation is parsed.
A shell will parse commands until it has a complete set of commands followed by a linefeed. This includes compound commands like { brace; groups; } and while loops; do true; done.
Example of incorrect code:
function checksum() {
type md5 && alias md5sum=md5
md5sum "$@" # This calls `md5sum`, not `md5`
}Example of correct code:
function checksum() {
type md5 && md5sum() { md5sum "$@"; }
md5sum "$@" # Now this would call `md5` when applicable
}