UNIX for Dummies Questions & Answers

I want to check (using bash condition test function) if string contains three spaces, ignoring last three spaces at the end of string.

Code:

string_to_report='foo bar   foo   bar   '
string_to_ignore='foo bar   '

Your question doesn't make any sense.
If statements don't read data from pipes.
You have shown us four echo statements (each of which prints at least three consecutive spaces piped into if statements with comments saying two of them don't contain three spaces???
Then you have shown us a conditional expression that performs two pathname expansions and performs logical and and not operations on those expansions in ways that might or might not be syntax errors depending on what files exist in the current directory.

If you want to write a function, the first thing you need to do is clearly explain what input that function is going to receive and what output it is supposed to produce.

You're right, I provided bad examples. See updated question.

Try

Code:

TMP="${string%   }"
[ "${TMP}" = "${TMP/   /}" ] && echo TRUE || echo FALSE

Hmm. Do you mean something like:

Code:

[ '   f f'~='[ ]{3}' ] && echo hi

This purposely does not directly answer your question, but shows what I think you mean.
By ignore - does that mean spaces at the end do not matter or you skip the comparison?

Thanks.

@jim: my bash man page talks of =~ within [[ ]]
And the ERE must be unquoted...

The updated spec is still ambiguous. The phrase: "ignoring three spaces at the end of the string" can be interpreted several ways. Any of them can be handled using standard variable expansions or conditional expressions in bash or any other shell that handles basic POSIX-mandated variable expansions.

Does it mean that the test fails if there aren't at least three spaces at the end of the string? And, then the test passes only if three spaces appear anywhere in the remainder of the string? If so, try:

Code:

[ "${var%   *   }" != "${var}" ] && echo pass || echo fail

Does it mean that the test passes if three spaces appear anywhere in the string other than the last three characters in the string? Try:

Code:

[ "${var%   ?*}" != "${var}" ] && echo pass || echo fail

Does it mean that the test passes if there are three spaces followed by a non-space character anywhere in the string? If so, try:

Code:

[ "${var%   [! ]*}" != "${var}" ] && echo pass || echo fail

Does it mean that the test passes if there are three spaces followed by any character (including another space) anywhere in the string, but if the string ends with three spaces none of those three spaces can be used in the match? If so, try:

Code:

tmp="${var%   }"
[ "${tmp%   *}" != "${tmp}" ] && echo pass || echo fail

Obviously, any of the above can be changed from using single square brackets:

Code:

[ "${var%pattern}" != "${var}" ] && echo pass || echo fail

to:

Code:

[[ "${var%pattern}" != "${var}" ]] && echo pass || echo fail
                  or
test "${var%pattern}" != "${var}" && echo pass || echo fail
                  or
if [ "${var%pattern}" != "${var}" ]
then    echo pass
else    echo fail
fi
                  etc.