On Tue, Feb 26, 2008 at 05:13:12PM -0600, Les Mikesell alleged: > Garrick Staples wrote: > >On Tue, Feb 26, 2008 at 04:33:30PM -0600, Les Mikesell alleged: > >>Does anyone have a quick reference to the order of operations as the > >>shell parses a command line (variable parsing,i/o redirection, wildcard > >>and variable expansion, splitting on IFS, quote removal, command > >>substitution etc.)? That's really the first thing you need to know > >>about the shell and if there is a simple description it must be buried > >>in the middle of some obscure manual. > > > >This is from the "EXPANSION" section of the bash manpage: > > > > The order of expansions is: brace expansion, tilde expansion, > > parameter, variable and arithmetic > > expansion and command substitution (done in a left-to-right > > fashion), word splitting, and pathname > > expansion. > > That's one step in the bigger picture. I want the one that includes > variable assignment, i/o redirection, quote removal, and a few other > operations. I think I knew that a few decades ago, but now I don't even > know where to look it up. That's pretty much the entire process for your basic expression. Quotes are obeyed the entire time, but are actually _removed_ after the expansion. And finally, file descriptors are opened the command is executed. I don't think you can write a simple list because the actual process is too complex. It would really be a tree or flowchart. -- Garrick Staples, GNU/Linux HPCC SysAdmin University of Southern California Please avoid sending me Word or PowerPoint attachments. See http://www.gnu.org/philosophy/no-word-attachments.html
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