Hi everybody.
I found the following bug while running some of my bash scripts on
GNU/Linux with stdout redirected to /dev/full, to see if write errors
where correctly detected and reported.
It turned out that, on write errors, the printf builtin correctly
returns a non-zero status (thus my scripts at least had a correct
exit status), but unfortunately it does not always display a suitable
error message on stderr; in particular, it fails to do so if the
printed string does *not* end with a newline. On the contrary, the
echo builtin both returns a non-zero status and write a clear error
message on standard error, even if called with the `-n' option (so
that the printed string does not end with a newline).
Examples (tested with both bash 3.2 and bash 4.0, more details about
versions and system information will follow):
$ ls -l /dev/full
crw-rw-rw- 1 root root 1, 7 Sep 2 18:36 /dev/full
$ cat printf-bug.sh
echo "* `type printf`"
echo "* `type echo`"
# - - -
printf x >/dev/full
echo a:$?
printf "%s\n" x >/dev/full
echo b:$?
echo -n x >/dev/full
echo c:$?
echo x >/dev/full
echo d:$?
# - - -
exit 0
$ bash printf-bug.sh # using either bash 4.0 or 3.2
* printf is a shell builtin
* echo is a shell builtin
a:1
printf-bug.sh: line 6: printf: write error: No space left on device
b:1
printf-bug.sh: line 8: echo: write error: No space left on device
c:1
printf-bug.sh: line 10: echo: write error: No space left on device
d:1
By the way, bash 3.0 behaves far worser (I don't known if you can
found this info useful, but anyway here it is):
$ bash-3.0 printf-bug.sh
* printf is a shell builtin
* echo is a shell builtin
a:0
b:0
c:1
d:1
Here are the details on my system and the bash shells used.
---
Details on operating system:
$ uname -s -r -m -o
Linux 2.6.26-1-686 i686 GNU/Linux
$ lsb_release -i -d -r -c
Distributor ID: Debian
Description: Debian GNU/Linux testing/unstable
Release: testing/unstable
Codename: n/a
$ cat /etc/debian_version
squeeze/sid
---
Details on bash versions:
Bash 4.0
---------------
Installed from debian package "bash", version "4.0-4"
Complete version string: 4.0.28(1)-release
Information from bashbug [Automatically generated]:
Machine: i486
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:
-DPROGRAM='bash'
-DCONF_HOSTTYPE='i486'
-DCONF_OSTYPE='linux-gnu'
-DCONF_MACHTYPE='i486-pc-linux-gnu'
-DCONF_VENDOR='pc'
-DLOCALEDIR='/usr/share/locale'
-DPACKAGE='bash'
-DSHELL
-DHAVE_CONFIG_H
-I. -I../bash -I../bash/include -I../bash/lib
-g -O2 -Wall
Machine Type: i486-pc-linux-gnu
Bash Version: 4.0
Patch Level: 28
Release Status: release
Bash 3.2
---------------
Installed by hand from official tarball.
Complete version string: 3.2.0(1)-release
Information from bashbug [Automatically generated]:
Machine: i686
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:
-DPROGRAM='bash'
-DCONF_HOSTTYPE='i686'
-DCONF_OSTYPE='linux-gnu'
-DCONF_MACHTYPE='i686-pc-linux-gnu'
-DCONF_VENDOR='pc'
-DLOCALEDIR='/opt/vintage/bash-3.2/share/locale'
-DPACKAGE='bash'
-DSHELL
-DHAVE_CONFIG_H
-I. -I. -I./include -I./lib
-g -O2
Machine Type: i686-pc-linux-gnu
Bash Version: 3.2
Patch Level: 0
Release Status: release
Bash 3.0
---------------
Installed by hand from official tarball.
Complete version string: 3.00.0(1)-release
Information from bashbug [Automatically generated]:
Machine: i686
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:
-DPROGRAM='bash'
-DCONF_HOSTTYPE='i686'
-DCONF_OSTYPE='linux-gnu'
-DCONF_MACHTYPE='i686-pc-linux-gnu'
-DCONF_VENDOR='pc'
-DLOCALEDIR='/opt/vintage/bash-3.0/share/locale'
-DPACKAGE='bash'
-DSHELL
-DHAVE_CONFIG_H
-I. -I. -I./include -I./lib
-g -O2
Machine Type: i686-pc-linux-gnu
Bash Version: 3.0
Patch Level: 0
Release Status: release
---
Regards,
Stefano
