In article <dd6183e6-29e2-4f7a-865d-0e085ca9f...@ri8g2000pbc.googlegroups.com>, bsh <brian_hi...@rocketmail.com> wrote:
> Janis Papanagnou <janis_papanag...@hotmail.com> wrote: > > Dan Stromberg wrote: > > > What should be the behavior of the following? > > > if cmd1 > > > then > > > cmd2 > > > fi && if cmd3 > > > then > > > cmd4 > > > fi > > Hello Daniel and Janis! > > > If cmd1 is true then execute cmd2; > > cmd2 defines the exit code for the first if > > depending on cmd2 return value, > > if true then the subsequent if is executed > > if cmd3 is true then execute cmd4; > > cmd4 defines the exit code for the second if > > I see a problem, which I cannot immediate test on a > command line available to me now. > > First of all, the manpage plainly indicates: > > "Usage: if if-list;then list[;elif list;then list]... [;else list];fi > ... If the if-list has a non-zero exit status and there is > no else-list, then the if command returns a zero exit status." > > > > Playing around, it appears that cmd1 and cmd3 have no > > > direct impact on the exit codes of the two if's, while > > > cmd2 and cmd4 do (if cmd1 or cmd3 evaluate true). > > Yes. cmd1 and cmd3 control the if condition, and the resulting > > exit code is defined by the last command executed, either cmd2 > > or cmd4. > > ... And because of this, it is impossible to discern whether > the return code is the result of a failed if-list or the > last command in the if-body code. This strikes me as poor > programming discipline. If you care about the exit status of the if-list, run it separately and save it. I.e. instead of: if cmd1; cmd2; ... then ... fi write: cmd1; cmd2; ... status=$? if [ $status = 0 ] then ... fi The assumption behind the design of "if" is that you only care about the success or failure of the if-list, not the specific kind of failure. -- Barry Margolin, bar...@alum.mit.edu Arlington, MA *** PLEASE post questions in newsgroups, not directly to me ***
