On 2019-03-27 13:50 +0100, Pierre Labastie via blfs-dev wrote: > Hi, > > When making scripts from the book (either by copy/paste > or some use of xsltproc), the generated scripts have `&&' at > the end of each line. It allows to not execute the following > instructions if one instructions fail, but it defeats the use of > "set -e". From the bash man page under the set builtin, for > option -e (emphasis by me): > ------------ > Exit immediately if a pipeline (which may consist of a > single simple command), a list, or a compound command > (see SHELL GRAMMAR above), exits with a non-zero status. > *The shell does not exit if the command that fails is > part of the command list immediately following a while > or until keyword, part of the test following the if or > elif reserved words, part of any command executed in a > && or || list except the command following the final && > or ||, any command in a pipeline but the last, or if the > command's return value is being inverted with !.*[...] > ------------ > In short, with a construct like: > ---- > set -e > instruction A && > instruction B && > instruction C > ---- > The script does not exit if either instruction A or instruction B fails, > but the following instructions are not executed... This may lead to > a script completing successfully, while the package was in fact not > installed, or only partially installed or compiled! > > So why do we use those `&&' in the book??? > > I've tried to automatically remove the `&&' in jhalfs, but it is not > possible, because sometimes, the `... && ...' construct really really means > if ...; then ... > > There could be a solution: ask devs not to use `... && ...' when they mean > if ...; then ... > > Another is to not have `&&' at the end of line. Actually, what would we > lose?
When I manually type the command I don't use `&&'. I just look at the terminal to make sure a command succeeds before typing the next. But when I copy the command, I think `&&' is useful or I have to run "bash -e". Maybe we can change these "&&" to "&amp;" in XML so jhalfs can define it to nothing or ";". After all, now "&" is "&" and "&amp;" is actually shorter than "&&" :). -- Xi Ruoyao <[email protected]> School of Aerospace Science and Technology, Xidian University -- http://lists.linuxfromscratch.org/listinfo/blfs-dev FAQ: http://www.linuxfromscratch.org/blfs/faq.html Unsubscribe: See the above information page
