Bash: (foo==0)?foo=1:foo=0 valid?
I seem to forget my shell programming but is the following statement valid? ($foo==0)?foo=1:foo=0 I thought it was called the tristate conditional operator but in any case I could not find it in google. -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
Re: Bash: (foo==0)?foo=1:foo=0 valid?
On 07/02/2011 10:45 AM, Daniel B. Thurman wrote: I seem to forget my shell programming but is the following statement valid? ($foo==0)?foo=1:foo=0 I thought it was called the tristate conditional operator but in any case I could not find it in google. I don't know if it's allowed in bash, or any other shell. I do know, however, that it's a valid construct in C. -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
Re: Bash: (foo==0)?foo=1:foo=0 valid?
On Saturday 02 July 2011 18:50:46 Joe Zeff wrote: On 07/02/2011 10:45 AM, Daniel B. Thurman wrote: I seem to forget my shell programming but is the following statement valid? ($foo==0)?foo=1:foo=0 I thought it was called the tristate conditional operator but in any case I could not find it in google. I don't know if it's allowed in bash, or any other shell. I do know, however, that it's a valid construct in C. With a small detail that the $ in $foo is not actually a valid C construct itself, right? Or were you looking at the subject line, where the code doesn't have the $? ;-) Best, :-) Marko -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
Re: Bash: (foo==0)?foo=1:foo=0 valid?
On 07/02/2011 11:01 AM, Marko Vojinovic wrote: With a small detail that the $ in $foo is not actually a valid C construct itself, right? Or were you looking at the subject line, where the code doesn't have the $? The trinary operator itself is a valid C construct, even though the example given wouldn't work. (Thanx for pointing out the error; it's been way, way too long since I actually did any programming and didn't notice it.) -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
Re: Bash: (foo==0)?foo=1:foo=0 valid?
On Sat, Jul 2, 2011 at 12:45 PM, Daniel B. Thurman d...@cdkkt.com wrote: I seem to forget my shell programming but is the following statement valid? ($foo==0)?foo=1:foo=0 I thought it was called the tristate conditional operator but in any case I could not find it in google. I think you might be looking for something similar to foo=$(($foo==0 ? 1 : 0)) John -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
Re: Bash: (foo==0)?foo=1:foo=0 valid?
On 07/02/2011 12:45 PM, Daniel B. Thurman wrote: I seem to forget my shell programming but is the following statement valid? ($foo==0)?foo=1:foo=0 I thought it was called the tristate conditional operator but in any case I could not find it in google. You need to enclose the entire expression in double parentheses to make bash parse it as an expression. Plus, your syntax is slightly wrong: ((($foo==0)?foo=1:0)) or, since within an expression the '$' to reference a variable is optional: (((foo==0)?foo=1:0)) and, if you want to insert the result directly into a command line: echo $(((foo==0)?1:0)) or echo $(((foo==0)?foo=1:0)) -- Bob Nichols NOSPAM is really part of my email address. Do NOT delete it. -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
Re: Bash: (foo==0)?foo=1:foo=0 valid?
On 07/02/2011 11:30 AM, Robert Nichols wrote: On 07/02/2011 12:45 PM, Daniel B. Thurman wrote: I seem to forget my shell programming but is the following statement valid? ($foo==0)?foo=1:foo=0 I thought it was called the tristate conditional operator but in any case I could not find it in google. You need to enclose the entire expression in double parentheses to make bash parse it as an expression. Plus, your syntax is slightly wrong: ((($foo==0)?foo=1:0)) or, since within an expression the '$' to reference a variable is optional: (((foo==0)?foo=1:0)) and, if you want to insert the result directly into a command line: echo $(((foo==0)?1:0)) or echo $(((foo==0)?foo=1:0)) Thanks - this is good information! I used: (((foo==0)?foo=1:0)) and it works in a bash script! Will add this to my bookmarks! :) -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
Re: Bash: (foo==0)?foo=1:foo=0 valid?
On Sat, Jul 2, 2011 at 2:07 PM, Daniel B. Thurman d...@cdkkt.com wrote: I used: (((foo==0)?foo=1:0)) and it works in a bash script! I don't think that is quite the same as what I'm guessing your original attempt intended. In this case if foo does not equal 0 to begin with it won't be set to 0. Perhaps that doesn't matter in your particular case. John -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
Re: Bash: (foo==0)?foo=1:foo=0 valid?
On Saturday, July 02, 2011 02:11:52 PM inode0 wrote: On Sat, Jul 2, 2011 at 2:07 PM, Daniel B. Thurman d...@cdkkt.com wrote: I used: (((foo==0)?foo=1:0)) and it works in a bash script! I don't think that is quite the same as what I'm guessing your original attempt intended. In this case if foo does not equal 0 to begin with it won't be set to 0. Perhaps that doesn't matter in your particular case. John If you know that foo is always initialized to either a value of zero or one, would the following seem reasonable? let foo=1-$foo -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
Re: Bash: (foo==0)?foo=1:foo=0 valid?
On 07/02/2011 02:11 PM, inode0 wrote: On Sat, Jul 2, 2011 at 2:07 PM, Daniel B. Thurmand...@cdkkt.com wrote: I used: (((foo==0)?foo=1:0)) and it works in a bash script! I don't think that is quite the same as what I'm guessing your original attempt intended. In this case if foo does not equal 0 to begin with it won't be set to 0. Perhaps that doesn't matter in your particular case. Indeed, I got it wrong too. Looks like it needs to be: (((foo==0)?(foo=1):(foo=0))) Frankly, I don't think I'll be using that syntax much. Too many ways to get it wrong. -- Bob Nichols NOSPAM is really part of my email address. Do NOT delete it. -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
Re: Bash: (foo==0)?foo=1:foo=0 valid?
On 07/02/2011 02:15 PM, Robert Nichols wrote: On 07/02/2011 02:11 PM, inode0 wrote: On Sat, Jul 2, 2011 at 2:07 PM, Daniel B. Thurmand...@cdkkt.com wrote: I used: (((foo==0)?foo=1:0)) and it works in a bash script! I don't think that is quite the same as what I'm guessing your original attempt intended. In this case if foo does not equal 0 to begin with it won't be set to 0. Perhaps that doesn't matter in your particular case. Indeed, I got it wrong too. Looks like it needs to be: (((foo==0)?(foo=1):(foo=0))) Frankly, I don't think I'll be using that syntax much. Too many ways to get it wrong. Yeah, you guys are correct, it does not toggle which was my intent. So I basically went back to the trusty if-else-fi statement of which anyone can read without much obscurity. :P Thanks to all, for contributing! -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
Re: Bash: (foo==0)?foo=1:foo=0 valid?
On Sat, 2011-07-02 at 14:31 -0700, Daniel B. Thurman wrote: On 07/02/2011 02:15 PM, Robert Nichols wrote: On 07/02/2011 02:11 PM, inode0 wrote: On Sat, Jul 2, 2011 at 2:07 PM, Daniel B. Thurmand...@cdkkt.com wrote: I used: (((foo==0)?foo=1:0)) and it works in a bash script! I don't think that is quite the same as what I'm guessing your original attempt intended. In this case if foo does not equal 0 to begin with it won't be set to 0. Perhaps that doesn't matter in your particular case. Indeed, I got it wrong too. Looks like it needs to be: (((foo==0)?(foo=1):(foo=0))) Frankly, I don't think I'll be using that syntax much. Too many ways to get it wrong. Yeah, you guys are correct, it does not toggle which was my intent. So I basically went back to the trusty if-else-fi statement of which anyone can read without much obscurity. :P Thanks to all, for contributing! ((foo=!foo)) or if using an interactive Shell: ((foo=\!foo)) poc -- users mailing list users@lists.fedoraproject.org To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
