Ruby Programming Language :: Is it possible to make system use bash instead of sh?


	Is it possible to make system use bash instead of sh? Hi, Does anyone know if it is possible to use bash instead of sh as the default shell when "system" is executed? For example, system("java --version") is executing java --version in sh, instead of bash, which can be a problem when I tried to do error redirection. -- Posted via http://www.ruby-forum.com/. Wai Tsang schrieb: > Hi, > Does anyone know if it is possible to use bash instead of sh as the > default shell when "system" is executed? System() should always call /bin/sh (on a POSIX compliant system), but of course you could still have sh call bash, like this: system("bash java --version") On 25.04.2007 17:43, Bjrn Paetzel wrote: > Wai Tsang schrieb: >> Does anyone know if it is possible to use bash instead of sh as the >> default shell when "system" is executed? > System() should always call /bin/sh (on a POSIX compliant system), Where did you get that information from? > but > of course you could still have sh call bash, like this: > system("bash java --version") Yes, of course. robert On 4/25/07, Wai Tsang <simo@gmail.com> wrote: > Hi, > Does anyone know if it is possible to use bash instead of sh as the > default shell when "system" is executed? > For example, system("java --version") is executing java --version in sh, > instead of bash, which can be a problem when I tried to do error > redirection. > -- > Posted via http://www.ruby-forum.com/. If bash is in your path you can do system("bash -c \"java -version\"") else you just have to put the full path, this works even on Windows :) Of course that is not exactly what you want, you would like to tell Kernel or whatever other object that wants to hear that kind of message: "You are going to use /bin/bash for system from now on". So I went digging the code, no such luck, I just could not find the definition of Kernel#system :( neither with rb_define_method.system nor with def\ssystem and even less with alias\ssystem or rb_alias.system Hope that somebody more learned will help us out here. Cheers Robert -- You see things; and you say Why? But I dream things that never were; and I say Why not? -- George Bernard Shaw On Apr 25, 2007, at 12:00 PM, Robert Klemme wrote: > On 25.04.2007 17:43, Bjrn Paetzel wrote: >> Wai Tsang schrieb: >>> Does anyone know if it is possible to use bash instead of sh as the >>> default shell when "system" is executed? >> System() should always call /bin/sh (on a POSIX compliant system), > Where did you get that information from? This behavior with respect to the Single Unix Specification is documented at: http://www.opengroup.org/onlinepubs/007908799/xsh/system.html Gary Wright On Thu, Apr 26, 2007 at 12:18:04AM +0900, Wai Tsang wrote: > Does anyone know if it is possible to use bash instead of sh as the > default shell when "system" is executed? system() with multiple arguments bypasses the shell. So try: system("/bin/bash", "-c", "java --version") -----BEGIN PGP SIGNED MESSAGE----- In article <335e48a90704250904y7c06bcb5s74b34cd86d928@mail.gmail.com>, - Hide quoted text - Robert Dober <robert.do@gmail.com> wrote: >On 4/25/07, Wai Tsang <simo@gmail.com> wrote: >Of course that is not exactly what you want, you would like to tell >Kernel or whatever other object that wants to hear that kind of >message: "You are going to use /bin/bash for system from now on". >So I went digging the code, no such luck, I just could not find the >definition of Kernel#system :( >neither with rb_define_method.system >nor with def\ssystem >and even less with >alias\ssystem >or >rb_alias.system >Hope that somebody more learned will help us out here. _ Ruby uses the underlying C exec call and any system that does not use /bin/sh is severely broken. It's part of the POSIX standard. If you want bash, then use the multi-arg form of the command which bypasses shell interpretation entirely. If you want the gory details look in process.c rb_f_system _ Booker C. Bense -----BEGIN PGP SIGNATURE----- Version: 2.6.2 iQCVAwUBRi+0jmTWTAjn5N/lAQEwgAP/SrYiy/UhXzHGJ4G4FJwP9XV72ogYvfbO CyhpNvaMdeBJEVp7lGl+Dw84fLlsQY6Dh9HBnzsyLv0vkpnOHByeQc+GVB9KdMYh C91ilHEPXQdI2QJPlMmnUh4H+fvRs5NgoNXIORhE4lnbsVXBDIcl73mXY0kHU82z fL4OcNifcnM= =EJLT -----END PGP SIGNATURE----- On Thu, Apr 26, 2007 at 01:46:25AM +0900, Gary Wright wrote: > This behavior with respect to the Single Unix > Specification is documented at: > http://www.opengroup.org/onlinepubs/007908799/xsh/system.html Standards like the Single Unix Specification (and the LSB, and so on) should be used as reasons for standardized behavior in a distributed OS, but they aren't really relevant to customized installs. If an end user wants to configure a system differently from the standard, that's his/her business. -- CCD CopyWrite Chad Perrin [ http://ccd.apotheon.org ] Leon Festinger: "A man with a conviction is a hard man to change. Tell him you disagree and he turns away. Show him facts and figures and he questions your sources. Appeal to logic and he fails to see your point." On Apr 25, 2007, at 11:18 AM, Wai Tsang wrote: > Hi, > Does anyone know if it is possible to use bash instead of sh as the > default shell when "system" is executed? Whenever 'system' is executed? Not sure about that. But what you might be able to do is have a new file that stores code which defines 'system2', and you could include that. It might be something like: def system2(command) system 'bash' system '#{command} end Of course, i have no clue (yet) how to use #{stuff} in my code, so any help would automatically be worthy of worship. Oh, and same with having two parameters in 'do' commands. Help? Please? HTH -------------------------------------------------------\| ~ Ari crap my sig won't fit On 4/25/07, Booker C. Bense <snip> > If you want the gory details look in process.c > rb_f_system Thx a lot, that's what I was looking for... > _ Booker C. Bense > -----BEGIN PGP SIGNATURE----- > Version: 2.6.2 > iQCVAwUBRi+0jmTWTAjn5N/lAQEwgAP/SrYiy/UhXzHGJ4G4FJwP9XV72ogYvfbO > CyhpNvaMdeBJEVp7lGl+Dw84fLlsQY6Dh9HBnzsyLv0vkpnOHByeQc+GVB9KdMYh > C91ilHEPXQdI2QJPlMmnUh4H+fvRs5NgoNXIORhE4lnbsVXBDIcl73mXY0kHU82z > fL4OcNifcnM= > =EJLT > -----END PGP SIGNATURE----- -- You see things; and you say Why? But I dream things that never were; and I say Why not? -- George Bernard Shaw On Apr 25, 2007, at 4:24 PM, Chad Perrin wrote: > On Thu, Apr 26, 2007 at 01:46:25AM +0900, Gary Wright wrote: >> This behavior with respect to the Single Unix >> Specification is documented at: >> http://www.opengroup.org/onlinepubs/007908799/xsh/system.html > Standards like the Single Unix Specification (and the LSB, and so on) > should be used as reasons for standardized behavior in a distributed > OS, but they aren't really relevant to customized installs. If an end > user wants to configure a system differently from the standard, that's > his/her business. I didn't see anyone claiming differently. I certainly wasn't. I just perceived the question as a desire for information about the standard. Wai Tsang <simo@gmail.com> writes: > Hi, > Does anyone know if it is possible to use bash instead of sh as the > default shell when "system" is executed? > For example, system("java --version") is executing java --version in sh, > instead of bash, which can be a problem when I tried to do error > redirection. > -- Others have indicated how you can execute the command with bash rather than sh. However, I'm interested in why you have problems with redirecting standard error with sh bat not bash. While I seem to remember bash offers some additional functionality, I thought redirecting of stdin/stdout/stderr was pretty similar, if not in syntax at least in functionality. Also, its been some time since I did java, but from memory, it uses quite a few shell wrapper scripts and they are all in sh rather than bash. Just interested. tim -- tcross (at) rapttech dot com dot au Thanks. System('bash','-c',cmd) does the task for me. -- Posted via http://www.ruby-forum.com/.