Cristian Ionescu-Idbohrn wrote:
sed (GNU sed) 4.2.2 can do this:
$ printf 'foo
bar
baz' | sed r -
foo
bar
baz
or, after storing the text in a file:
$ printf 'foo
bar
baz' >/tmp/bar
$ sed r /tmp/bar
foo
bar
baz
But busybox sed can't:
$ printf 'foo
bar
baz' | busybox sed r -
sed: empty filename
$ busybox sed r /tmp/bar
sed: empty filename
$ printf '' | busybox sed 'r /tmp/bar'
<no output, although /tmp/bar size is 11 bytes>
$ busybox sed 'r /tmp/bar'
<waiting for stdin; ^D; no output>
The 'r' command is documented by GNU sed as a GNU extension. Still,
busybox sed documents the 'r' command as supported:
r [address]r file
Read contents of file and append after the contents of the
pattern space. Exactly one space must be put between r and the
filename.
Am I misinterpreting the documentation?
From the documentation:
> The full format for invoking `sed' is:
> sed OPTIONS... [SCRIPT] [INPUTFILE...]
So in your example you invoce sed with the script "r" and the input file
"-" or "/tmp/bar". The content is not printed because it is the argument
to the "r" command, but because it is the main input file to sed. You
can avoid that by using quotes around the command and the file name, or
by omitting the space between the command and the filename.
You should also try the last two examples, where you invoke busybox sed
with quotes, with GNU sed. The behaviour is the same.
You should note that in your example when reading from a file, sed
didn't read from stdin, at least you don't mention it, although your
interpretation would mean that the filename is the argument to the "r"
command, therefor no argument is given to sed, and sed should read stdin.
You should also not that invoking the "r" command with the filename
causes the content of this file to be inserted after every line. When
reading from a pipe, the pipe is empty after the first line.
My documentation to GNU sed 4.2.2 says:
> `r FILENAME'
> As a GNU extension, this command accepts two addresses.
>
> Queue the contents of FILENAME to be read and inserted into the
> output stream at the end of the current cycle, or when the next
> input line is read. Note that if FILENAME cannot be read, it is
> treated as if it were an empty file, without any error indication.
>
> As a GNU `sed' extension, the special value `/dev/stdin' is
> supported for the file name, which reads the contents of the
> standard input.
So the main difference seems to be that GNU sed doesn't give an error
message if the file can't be read. I'm not sure why that would be a good
idea.
Also not that there is no mention of using "r -" for stdin, instead
/dev/stdin is mentioned.
On the other hand, I don't know why busybox sed needs exactly one space
between command and filename. GNU sed works with zero or more spaces.
_______________________________________________
busybox mailing list
busybox@busybox.net
http://lists.busybox.net/mailman/listinfo/busybox
