This is the mail archive of the cygwin mailing list for the Cygwin project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

bug with built-in commands in bash when redirecting output

The following one liner illustrates a bug in sh:
$ /bin/bash -c '/bin/bash -cx '\''x=`echo hello`'\''' > @x
++ echo hello
+ x=$'hello\r'

The problem is as follows.  When a built-in shell command (such as pwd
or echo) is executed within back quotes (or within $(...)) when the
shell's output is redirected to a file, the command produces \r\n at the
end of the line of which only the final \n is removed.

Normally when a command is executed within back quotes, the final line
ending is removed before the result is substituted.  That happens here
also, but the difference is that there is still a \r at the end.

When the echo command in the above example is replace by /bin/echo, the
result is correct (i.e. no \r in the assignment to x):

$ /bin/bash -c '/bin/bash -cx '\''x=`/bin/echo hello`'\''' > @x
++ /bin/echo hello
+ x=hello

The bug, it seems to me, is that the shell checks that its output is
redirected to a file and that it therefore has to write \r\n at the end
of each line.  So far so good.  However, when it executes a built-in
command within back quotes, it still uses this knowledge and still
writes \r\n.

It may be relevant that I have Cygwin configured to use DOS line
endings.  Also, my Cygwin installation is up-to-date (except for pending
updates to readline).  My bash version is 3.2.9-10.

Sjoerd Mullender

Attachment: signature.asc
Description: OpenPGP digital signature

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]