如何在bash中对文本文件的行进行块排序？

Question

I have a bar-separated text file that looks like this:

stringC|rest-of-lineC3
stringC|rest-of-lineC1
stringC|rest-of-lineC2
stringA|rest-of-lineA2
stringA|rest-of-lineA1
stringB|rest-of-lineB4
stringB|rest-of-lineB1
stringB|rest-of-lineB3
stringB|rest-of-lineB2

I need to block-sort it by the string before the | without doing secondary sort of what comes after the bar. So the example below SHOULD be sorted into:

stringA|rest-of-lineA2
stringA|rest-of-lineA1
stringB|rest-of-lineB4
stringB|rest-of-lineB1
stringB|rest-of-lineB3
stringB|rest-of-lineB2
stringC|rest-of-lineC3
stringC|rest-of-lineC1
stringC|rest-of-lineC2

but NOT into:

stringA|rest-of-lineA1
stringA|rest-of-lineA2
stringB|rest-of-lineB1
...

Is there a way of doing this in a bash script using sort or any other commands?

How can I get the same result as above in case the original file is not in blocks, ie it looks something like this:

stringC|rest-of-lineC3
stringA|rest-of-lineA2
stringC|rest-of-lineC1
stringA|rest-of-lineA1
stringB|rest-of-lineB4
stringB|rest-of-lineB1
stringC|rest-of-lineC2
stringB|rest-of-lineB3
stringB|rest-of-lineB2

Answer 1

sort with -s option for stable

sort -st'|' -k1,1 file

initial blocks doesn't matter, should work for both.