Problem Statement

The task is to remove text that follow any of a set of comment markers, (in these examples either a hash or a semicolon) from a string or input line.

Whitespace debacle:   There is some confusion about whether to remove any whitespace from the input line. As of 2 September 2011, at least 8 languages (C, C++, Java, Perl, Python, Ruby, sed, UNIX Shell) were incorrect, out of 36 total languages, because they did not trim whitespace by 29 March 2011 rules. Some other languages might be incorrect for the same reason. Please discuss this issue at Talk:Strip comments from a string.

The following examples will be truncated to either "apples, pears " or "apples, pears". (This example has flipped between "apples, pears " and "apples, pears" in the past.)

Let's start with the solution:

bash$ a='apples, pears ; and bananas'
bash$ b='apples, pears # and bananas'
bash$ echo ${a%%;*}
apples, pears
bash$ echo ${b%%#*}
apples, pears
bash$