ian@hpopd.HP.COM (Ian Watson) (10/17/90)
What's the point of the -n option for the 'set' command of sh ? -n Reads commands but does not execute them If you have set it, how would you ever unset it ? ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Ian Watson, HP Pinewood Information Systems Division, England. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Phone : (Intl)+44 344 763015 Unix mail (Internet) : ian@hpopd.HP.COM Unix mail (UUCP) : ...!hplabs!hpopd!ian Openmail : ian watson/pinewood,lab,hpopd Openmail from Unix : ian_watson/pinewood_lab_hpopd@hpopd HPDesk : Ian WATSON/HP1600 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cbrandau@isis.cs.du.edu (carl brandauer) (10/19/90)
In article <23880001@hpopd.HP.COM> ian@hpopd.HP.COM (Ian Watson) writes: >What's the point of the -n option for the 'set' command of sh ? > > -n Reads commands but does not execute them > >If you have set it, how would you ever unset it ? When writing shell scripts, 'set -n' is useful for detecting syntax errors without risking the dangers that might occur if every command were executed. If you set -n on the command line, logging off is the only way to unset it.
jms@tardis.Tymnet.COM (Joe Smith) (10/20/90)
Q: What is "-n" good for in /bin/sh?
A: "sh -nv shell_script_being_debugged".
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San Jose, CA 95161-9019 | humorous dislaimer: "My Amiga 3000 speaks for me."martin@mwtech.UUCP (Martin Weitzel) (10/23/90)
In article <1295@tardis.Tymnet.COM> jms@tardis.Tymnet.COM (Joe Smith) writes: >Q: What is "-n" good for in /bin/sh? >A: "sh -nv shell_script_being_debugged". True answer, but there's an interesting bug, at least in some flavours of UNIX SysV: A script containing .... while read a do ... something .... done .... hangs, even if you "debug" it with the -n option of the shell set. Note further, that if you substitute an `if' for the `while' in the above example, everything is fine. Though I can understand that bugs like this may slip into a program (execution of the internal command `read' is not properly inhibited) I allways wondered about the differences depending on the if/while context. Is there anybody out there with more insight (esp. someone with access to the shell sources?) -- Martin Weitzel, email: martin@mwtech.UUCP, voice: 49-(0)6151-6 56 83
boyd@necisa.ho.necisa.oz (Boyd Roberts) (10/23/90)
In article <23880001@hpopd.HP.COM> ian@hpopd.HP.COM (Ian Watson) writes: >What's the point of the -n option for the 'set' command of sh ? > Try: sh -n script Ok? Boyd Roberts boyd@necisa.ho.necisa.oz.au ``When the going gets wierd, the weird turn pro...''