| Message ID | 1395052954-1567-1-git-send-email-yann.morin.1998@free.fr |
|---|---|
| State | Rejected |
| Headers | show |
>>>>> "Yann" == Yann E MORIN <yann.morin.1998@free.fr> writes: > From: "Yann E. MORIN" <yann.morin.1998@free.fr> > The way we are checking for bash is to look if "$SHELL --version" > will return a string containing "^GNU bash". > In case the system shell is dash (eg. /bin/sh -> /bin/dash), but > the user's login shell is bash, dash will not override the SHELL > variable: > $ echo $SHELL > /bin/bash > $ /bin/dash > $$ echo $SHELL > /bin/bash > The same happens when called as the interpreter for a shell script: > $ cat foo.sh > #!/bin/dash > echo $SHELL > $ echo $SHELL > /bin/bash > $ ./foo.sh > /bin/bash > So, calling "$SHELL --version" will still return "^GNU bash" no matter > what shell is actually running. > Since quite a lot of #!/bin/sh scripts are in fact bash scripts, we > really want to ensure that /bin/sh is bash. Is that really still an issue? I just checked a few of the machines I often do buildroot builds on and they all have /bin/sh == dash. > -# Check bash > -if ! $SHELL --version 2>&1 | grep -q '^GNU bash'; then > +# Check bash is the system shell > +if ! /bin/sh --version 2>&1 | grep -q '^GNU bash'; then FYI, dash doesn't even understand a --version argument: sh --version sh: 0: Illegal option --
Peter, All, On 2014-03-17 22:28 +0100, Peter Korsgaard spake thusly: > >>>>> "Yann" == Yann E MORIN <yann.morin.1998@free.fr> writes: > > > From: "Yann E. MORIN" <yann.morin.1998@free.fr> > > The way we are checking for bash is to look if "$SHELL --version" > > will return a string containing "^GNU bash". > > > In case the system shell is dash (eg. /bin/sh -> /bin/dash), but > > the user's login shell is bash, dash will not override the SHELL > > variable: > > > $ echo $SHELL > > /bin/bash > > $ /bin/dash > > $$ echo $SHELL > > /bin/bash > > > The same happens when called as the interpreter for a shell script: > > > $ cat foo.sh > > #!/bin/dash > > echo $SHELL > > > $ echo $SHELL > > /bin/bash > > $ ./foo.sh > > /bin/bash > > > So, calling "$SHELL --version" will still return "^GNU bash" no matter > > what shell is actually running. > > > Since quite a lot of #!/bin/sh scripts are in fact bash scripts, we > > really want to ensure that /bin/sh is bash. > > Is that really still an issue? I just checked a few of the machines I > often do buildroot builds on and they all have /bin/sh == dash. Some configure-y scripts will run with /bin/sh, but have bashisms in them. It was reported on IRC by Andrew that switching the system shell from dash to bash fixed an issue (Andrew, was that with libxml2?). > > -# Check bash > > -if ! $SHELL --version 2>&1 | grep -q '^GNU bash'; then > > +# Check bash is the system shell > > +if ! /bin/sh --version 2>&1 | grep -q '^GNU bash'; then > > FYI, dash doesn't even understand a --version argument: Yes, but it surely does not return something matching "^GNU bash" which is all we care about. Regards, Yann E. MORIN.
>>>>> "Yann" == Yann E MORIN <yann.morin.1998@free.fr> writes: > Peter, All, >> Is that really still an issue? I just checked a few of the machines I >> often do buildroot builds on and they all have /bin/sh == dash. > Some configure-y scripts will run with /bin/sh, but have bashisms in them. > It was reported on IRC by Andrew that switching the system shell from > dash to bash fixed an issue (Andrew, was that with libxml2?). I don't think it is libxml2 as the stuff I'm currently doing at $WORK uses libxml2 and I haven't seen any issues with /bin/sh = dash. >> > -# Check bash >> > -if ! $SHELL --version 2>&1 | grep -q '^GNU bash'; then >> > +# Check bash is the system shell >> > +if ! /bin/sh --version 2>&1 | grep -q '^GNU bash'; then >> >> FYI, dash doesn't even understand a --version argument: > Yes, but it surely does not return something matching "^GNU bash" which > is all we care about. True.
Dear Yann E. MORIN, On Mon, 17 Mar 2014 11:42:34 +0100, Yann E. MORIN wrote: > So, calling "$SHELL --version" will still return "^GNU bash" no matter > what shell is actually running. > > Since quite a lot of #!/bin/sh scripts are in fact bash scripts, we > really want to ensure that /bin/sh is bash. I'm definitely against that. My system has /bin/sh pointing to dash, and Buildroot works fine. One of the thing that annoyed me in OpenEmbedded was its requirements to have /bin/sh be bash. We clearly don't want that. I've just checked the Free Electrons autobuilders, and there are also using dash as /bin/sh. This means that if configure scripts were using bashims unsupported by dash, we would have noticed. Thomas
Thomas, All, On 2014-03-18 06:01 +0100, Thomas Petazzoni spake thusly: > On Mon, 17 Mar 2014 11:42:34 +0100, Yann E. MORIN wrote: > > > So, calling "$SHELL --version" will still return "^GNU bash" no matter > > what shell is actually running. > > > > Since quite a lot of #!/bin/sh scripts are in fact bash scripts, we > > really want to ensure that /bin/sh is bash. > > I'm definitely against that. My system has /bin/sh pointing to dash, > and Buildroot works fine. One of the thing that annoyed me in > OpenEmbedded was its requirements to have /bin/sh be bash. > > We clearly don't want that. I'm just fine with that. :-) But the current check is broken anyway, as all it checks is that the login shell of the user is bash. - if we want to work whith dash as the system shell, then the current check is unneeded; - if we want to work with dash as the system shell, we don't care what login shell the user is using, as we must also work when this is dash; - SHELL is not mandated by POSIX, so it may be empty on a POSIX-compliant shell anyway. So, we should just remove this check altogether. > I've just checked the Free Electrons autobuilders, and there are also > using dash as /bin/sh. This means that if configure scripts were using > bashims unsupported by dash, we would have noticed. Andrew, what package was the breakage due to? Regards, Yann E. MORIN.
Dear Yann E. MORIN, On Tue, 18 Mar 2014 17:55:18 +0100, Yann E. MORIN wrote: > > I'm definitely against that. My system has /bin/sh pointing to dash, > > and Buildroot works fine. One of the thing that annoyed me in > > OpenEmbedded was its requirements to have /bin/sh be bash. > > > > We clearly don't want that. > > I'm just fine with that. :-) > > But the current check is broken anyway, as all it checks is that the > login shell of the user is bash. > > - if we want to work whith dash as the system shell, then the current > check is unneeded; > > - if we want to work with dash as the system shell, we don't care what > login shell the user is using, as we must also work when this is dash; > > - SHELL is not mandated by POSIX, so it may be empty on a > POSIX-compliant shell anyway. > > So, we should just remove this check altogether. Yes, I agree. Thomas
On 18/03/14 17:55, Yann E. MORIN wrote: > Thomas, All, > > On 2014-03-18 06:01 +0100, Thomas Petazzoni spake thusly: >> On Mon, 17 Mar 2014 11:42:34 +0100, Yann E. MORIN wrote: >> >>> So, calling "$SHELL --version" will still return "^GNU bash" no matter >>> what shell is actually running. Have you tested this? dependencies.sh is run from the Makefile, and that says: SHELL:=$(shell if [ -x "$$BASH" ]; then echo $$BASH; \ else if [ -x /bin/bash ]; then echo /bin/bash; \ else echo sh; fi; fi) [snip] export SHELL CONFIG_SHELL quiet Q KBUILD_VERBOSE VERBOSE So $SHELL _will_ be set to bash unless there is no bash. >>> >>> Since quite a lot of #!/bin/sh scripts are in fact bash scripts, we >>> really want to ensure that /bin/sh is bash. >> >> I'm definitely against that. My system has /bin/sh pointing to dash, >> and Buildroot works fine. One of the thing that annoyed me in >> OpenEmbedded was its requirements to have /bin/sh be bash. >> >> We clearly don't want that. > > I'm just fine with that. :-) > > But the current check is broken anyway, as all it checks is that the > login shell of the user is bash. > > - if we want to work whith dash as the system shell, then the current > check is unneeded; > > - if we want to work with dash as the system shell, we don't care what > login shell the user is using, as we must also work when this is dash; > > - SHELL is not mandated by POSIX, so it may be empty on a > POSIX-compliant shell anyway. > > So, we should just remove this check altogether. Not remove, but rather replace it with a check for /bin/bash existence. We do have quite a lot of stuff referring to /bin/bash. bash in PATH is not good enough. Regards, Arnout > >> I've just checked the Free Electrons autobuilders, and there are also >> using dash as /bin/sh. This means that if configure scripts were using >> bashims unsupported by dash, we would have noticed. > > Andrew, what package was the breakage due to? > > Regards, > Yann E. MORIN. >
diff --git a/support/dependencies/dependencies.sh b/support/dependencies/dependencies.sh index a8261b3..1b1a825 100755 --- a/support/dependencies/dependencies.sh +++ b/support/dependencies/dependencies.sh @@ -138,11 +138,16 @@ if [ ! -z "$CXXCOMPILER" ] ; then fi fi -# Check bash -if ! $SHELL --version 2>&1 | grep -q '^GNU bash'; then +# Check bash is the system shell +if ! /bin/sh --version 2>&1 | grep -q '^GNU bash'; then echo - echo "You must install 'bash' on your build machine"; - exit 1; + echo "You must install 'bash' on your build machine" + echo "and make it your default shell. On Debian-like" + echo "systems, this can be done with:" + echo " sudo dpkg-reconfigure dash" + echo "and answer 'No' to the question:" + echo " Use dash as the default system shell (/bin/sh)?" + exit 1 fi; # Check that a few mandatory programs are installed