printf does not always display warning messages on write errors
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
ulimit and ssh?
Can someone explain this to me? Why am I not seeing correct results from ulimit after ssh into localhost? Thanks! $ ssh localhost bash -c 'ulimit -a' unlimited but $ bash -c 'ulimit -a' core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 32768 max locked memory (kbytes, -l) 32 max memory size (kbytes, -m) unlimited open files (-n) 1024 pipe size(512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 10240 cpu time (seconds, -t) unlimited max user processes (-u) 1024 virtual memory (kbytes, -v) unlimited file locks (-x) unlimited -- View this message in context: http://www.nabble.com/ulimit-and-ssh--tp25262471p25262471.html Sent from the Gnu - Bash mailing list archive at Nabble.com.
Re: ulimit and ssh?
peter360 wrote: Can someone explain this to me? Why am I not seeing correct results from ulimit after ssh into localhost? Thanks! $ ssh localhost bash -c 'ulimit -a' unlimited You have insufficiently quoted your argument to ssh. This is causing bash not to get ulimit -a but to get ulimit -a instead. You are seeing the output of ulimit. Try this: ssh localhost bash -c 'ulimit -a' And this: echo ulimit -a | ssh localhost bash Bob
Re: ulimit and ssh?
Bob, Thanks for the quick reply! A local unix guru also told me the same thing. So, just to make sure I really understand this, here is how I understand ssh worked: even thought I gave the command bash -c 'ulimit -a' as 3 separate strings, ssh (either the client or the server) actually concatenate them into one, and sshd forks a shell to parse the concatenated command string, in this case bash -c ulimit -a.Correct me if I am wrong. Glad I learned something new. Bob Proulx wrote: peter360 wrote: Can someone explain this to me? Why am I not seeing correct results from ulimit after ssh into localhost? Thanks! $ ssh localhost bash -c 'ulimit -a' unlimited You have insufficiently quoted your argument to ssh. This is causing bash not to get ulimit -a but to get ulimit -a instead. You are seeing the output of ulimit. Try this: ssh localhost bash -c 'ulimit -a' And this: echo ulimit -a | ssh localhost bash Bob -- View this message in context: http://www.nabble.com/ulimit-and-ssh--tp25262471p25263766.html Sent from the Gnu - Bash mailing list archive at Nabble.com.
Re: ulimit and ssh?
peter360 wrote: So, just to make sure I really understand this, here is how I understand ssh worked: even thought I gave the command bash -c 'ulimit -a' as 3 separate strings, Yes. ssh (either the client or the server) actually concatenate them into one, No. It isn't put into one string unless you quote it as one string. and sshd forks a shell to parse the concatenated command string, in this case bash -c ulimit -a.Correct me if I am wrong. On the remote server a $SHELL (specified in /etc/passwd, not necessarly the same shell as on the client machine, a long standing issue with rsh/ssh) parses the arguments /again/. Which means you almost always need two layers of quoting if quoting is needed. One for the local shell. One more for the remote shell. echo ulimit -a | ssh localhost bash This style avoids the quoting problem entirely and guarentees that the remote shell is bash regardless of different /etc/passwd configuration. However it does use stdin and it is no longer available for the remote command, if that is important. Useful when it can be used however. Also, my example had a problem. ssh localhost bash -c 'ulimit -a' I should have added the -n option to ssh so that it wouldn't read from stdin. In the above if used in a script it will read and consume any input that may have been expected for a different command. ssh -n localhost bash -c 'ulimit -a' Bob
Re: printf does not always display warning messages on write errors
Stefano Lattarini wrote: 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. Thanks for the report. This will be fixed in the next version. Chet -- ``The lyf so short, the craft so long to lerne.'' - Chaucer ``Ars longa, vita brevis'' - Hippocrates Chet Ramey, ITS, CWRUc...@case.eduhttp://cnswww.cns.cwru.edu/~chet/
RE: Who handles fails to build problems for bash?
Tried adding each of -lcurses and -lncurses with the following results: /home/users/tovrea/local/sgi6/bin/gcc -L./builtins -L./lib/readline -L./lib/readline -L./lib/glob -L./lib/tilde -L./lib/sh -L/home/users/tovrea/local/sgi6/lib/gcc/mips-sgi-irix6.5/4.3.0 -L/home/users/tovrea/local/sgi6/lib/gcc/mips-sgi-irix6.5/4.3.0/32 -L/home/users/tovrea/local/sgi6/lib/gcc/mips-sgi-irix6.5/lib32 -L/home/users/tovrea/local/sgi6/lib-g -O2 -o bash shell.o eval.o y.tab.o general.o make_cmd.o print_cmd.o dispose_cmd.o execute_cmd.o variables.o copy_cmd.o error.o expr.o flags.o jobs.o subst.o hashcmd.o hashlib.o mailcheck.o trap.o input.o unwind_prot.o pathexp.o sig.o test.o version.o alias.o array.o arrayfunc.o braces.o bracecomp.o bashhist.o bashline.o list.o stringlib.o locale.o findcmd.o redir.o pcomplete.o pcomplib.o syntax.o xmalloc.o -lbuiltins -lsh -lreadline -lhistory -ltermcap -lcurses -lglob -ltilde lib/intl/libintl.a -ldl /home/users/tovrea/local/sgi6/bin/ld: non-dynamic relocations refer to dynamic symbol PC /home/users/tovrea/local/sgi6/bin/ld: failed to set dynamic section sizes: Bad value collect2: ld returned 1 exit status /home/users/tovrea/local/sgi6/bin/gcc -L./builtins -L./lib/readline -L./lib/readline -L./lib/glob -L./lib/tilde -L./lib/sh -L/home/users/tovrea/local/sgi6/lib/gcc/mips-sgi-irix6.5/4.3.0 -L/home/users/tovrea/local/sgi6/lib/gcc/mips-sgi-irix6.5/4.3.0/32 -L/home/users/tovrea/local/sgi6/lib/gcc/mips-sgi-irix6.5/lib32 -L/home/users/tovrea/local/sgi6/lib-g -O2 -o bash shell.o eval.o y.tab.o general.o make_cmd.o print_cmd.o dispose_cmd.o execute_cmd.o variables.o copy_cmd.o error.o expr.o flags.o jobs.o subst.o hashcmd.o hashlib.o mailcheck.o trap.o input.o unwind_prot.o pathexp.o sig.o test.o version.o alias.o array.o arrayfunc.o braces.o bracecomp.o bashhist.o bashline.o list.o stringlib.o locale.o findcmd.o redir.o pcomplete.o pcomplib.o syntax.o xmalloc.o -lbuiltins -lsh -lreadline -lhistory -ltermcap -lncurses -lglob -ltilde lib/intl/libintl.a -ldl /home/users/tovrea/local/sgi6/bin/ld: cannot find -lncurses collect2: ld returned 1 exit status I also tried configuring with --with-curses but had the same result. I also took a look at config.log. It indicates it cannot find termcap.h but does find libtermcap (there is one located at /usr/lib). Didn't see any other problems. -Original Message- From: Chet Ramey [mailto:c...@caleb.ins.cwru.edu] On Behalf Of Chet Ramey Sent: Tuesday, September 01, 2009 2:52 PM To: Tovrea, George W (US SSA) Cc: bug-bash@gnu.org; c...@po.cwru.edu Subject: Re: Who handles fails to build problems for bash? Could not find any groups other than this for bash problems. My build is failing with make[1]: Leaving directory `/home/users/tovrea/BASH/build_sgi_bash/lib/tilde' rm -f bash /home/users/tovrea/local/sgi6/bin/gcc -L./builtins -L./lib/readline -L./lib/readline -L./lib/glob -L./lib/tilde -L./lib/sh -L/home/users/tovrea/local/sgi6/lib/gcc/mips-sgi-irix6.5/4.3.0 -L/home/users/tovrea/local/sgi6/lib/gcc/mips-sgi-irix6.5/4.3.0/32 -L/home/users/tovrea/local/sgi6/lib/gcc/mips-sgi-irix6.5/lib32 -L/home/users/tovrea/local/sgi6/lib-g -O2 -o bash shell.o eval.o y.tab.o general.o make_cmd.o print_cmd.o dispose_cmd.o execute_cmd.o variables.o copy_cmd.o error.o expr.o flags.o jobs.o subst.o hashcmd.o hashlib.o mailcheck.o trap.o input.o unwind_prot.o pathexp.o sig.o test.o version.o alias.o array.o arrayfunc.o braces.o bracecomp.o bashhist.o bashline.o list.o stringlib.o locale.o findcmd.o redir.o pcomplete.o pcomplib.o syntax.o xmalloc.o -lbuiltins -lsh -lreadline -lhistory -ltermcap -lglob -ltilde lib/intl/libintl.a -ldl /home/users/tovrea/local/sgi6/bin/ld: non-dynamic relocations refer to dynamic symbol PC /home/users/tovrea/local/sgi6/bin/ld: failed to set dynamic section sizes: Bad value collect2: ld returned 1 exit status make: *** [bash] Error 1 The quick fix should be adding -lcurses or -lncurses (whatever works) as the value of TERMCAP_LIB in the= Makefile. The longer fix is to look at config.log and try and figure out why there is (apparently) no library that contains the termcap functions, and why the build process is not defaulting to the built-in termcap library if so. Chet -- ``The lyf so short, the craft so long to lerne.'' - Chaucer ``Ars longa, vita brevis'' - Hippocrates Chet Ramey, ITS, CWRUc...@case.eduhttp://cnswww.cns.cwru.edu/~chet/
