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Home > Archive > Unix Shell > February 2005 > how to execute new command with awk - if/then/else?
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how to execute new command with awk - if/then/else?
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| martin 2005-02-06, 8:47 pm |
| i'm trying to figure out the syntax for building an awk statement that
will check the output of text in a file generated after attempting to
compile a source code file. i'm new to unix and don't know how to
issue statements to terminal if they're embedded inside an if/then
control statement.
../alan 3build6.alan > alan_output.txt ; awk (if ~/No warnings or errors
detected/ printf ./arun 3build6); else print "compile wasn't a success"
i'm trying to tell terminal to run the executable file by issuing a
command "./arun 3build6" if the string "No warnings or errors detected"
exists in the alan_output.txt file. once i understand that - i'd also
like to add some other more sophisticated commands in the "else"
portion of the code... but for now, i was just using the "compile
wasn't a success" as a way of checking the code's functionality.
i found on some of the awk pages that some examples used the printf
command - but i don't know what that does. i do now want - or do not
need for: "./arun 3build6" to be printed to the terminal screen unless
it will be printed into a command line, with the equivilant of hitting
the return button to execute it.
any wisdom would really be appreciated. 
thank you.
martin
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| Chris F.A. Johnson 2005-02-06, 8:47 pm |
| On Mon, 07 Feb 2005 at 01:19 GMT, martin wrote:
> i'm trying to figure out the syntax for building an awk statement that
> will check the output of text in a file generated after attempting to
> compile a source code file. i'm new to unix and don't know how to
> issue statements to terminal if they're embedded inside an if/then
> control statement.
>
> ./alan 3build6.alan > alan_output.txt ; awk (if ~/No warnings or errors
> detected/ printf ./arun 3build6); else print "compile wasn't a success"
>
> i'm trying to tell terminal to run the executable file by issuing a
> command "./arun 3build6" if the string "No warnings or errors detected"
> exists in the alan_output.txt file. once i understand that - i'd also
> like to add some other more sophisticated commands in the "else"
> portion of the code... but for now, i was just using the "compile
> wasn't a success" as a way of checking the code's functionality.
>
> i found on some of the awk pages that some examples used the printf
> command - but i don't know what that does. i do now want - or do not
> need for: "./arun 3build6" to be printed to the terminal screen unless
> it will be printed into a command line, with the equivilant of hitting
> the return button to execute it.
>
> any wisdom would really be appreciated.
I don't know just what you are trying to do, but perhaps this will
help.
To run one command when a previous command exits successfully, and
another when it fails:
if command
then
: successful command here
else
: unsuccessful command here
fi
I you need to check for the existence of something in the first
command's output, use the success or failure of grep:
command | ## tee alan_output.txt | ## uncomment to also save output in a file
if grep "No warnings or errors detected" >/dev/null
then
: successful command here
else
: unsuccessful command here
fi
--
Chris F.A. Johnson http://cfaj.freeshell.org/shell
========================================
===========================
My code (if any) in this post is copyright 2005, Chris F.A. Johnson
and may be copied under the terms of the GNU General Public License
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| Ed Morton 2005-02-07, 2:47 am |
|
martin wrote:
> i'm trying to figure out the syntax for building an awk statement that
> will check the output of text in a file generated after attempting to
> compile a source code file. i'm new to unix and don't know how to
> issue statements to terminal if they're embedded inside an if/then
> control statement.
>
> ./alan 3build6.alan > alan_output.txt ; awk (if ~/No warnings or errors
> detected/ printf ./arun 3build6); else print "compile wasn't a success"
Much as I like awk, it seems inappropriate for what you appear to be
trying to do. Try this:
../alan 3build6.alan > alan_output.txt
if grep "No warnings or errors detected" alan_output.txt >/dev/null
then
./arun 3build6
else
printf "compile wasn't a success\n"
endif
If the command "allan" exits with a failure code when it issues a
warning (debatable if it should) or error (almost certainly should),
then you could simplify the above to:
if ./alan 3build6.alan > alan_output.txt
then
./arun 3build6
else
printf "compile wasn't a success\n"
endif
Regards,
Ed.
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| martin 2005-02-07, 7:50 am |
| Thanks for writing back (everyone). I'm so new to unix and terminal
that i haven't yet figured out how to do two things -(among about a
million other things
one - type multi line commands into the terminal w/out terminal wanting
to process the first line after hitting return... or setting up a code
file for terminal to fetch to collect statements to run
and, two - how to just type the code you wrote above on one line using
";" to seperate each command.
since i think it'll be easier to put it all in one line (as i'm going
to have to have applescript send that line to terminal) could you
possibly re-type what you wrote above, and show me the format for doing
it all in one command line? when i tried last night, i kept getting
errors about how the ( ) were in the wrong place - (some examples i'd
seen used curly braces and ( ) and i was trying to follow that
syntax...)
i would really appreciate being able to see both side-by-side.
thanks so much!
martin
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| Chris F.A. Johnson 2005-02-07, 7:50 am |
| On Mon, 07 Feb 2005 at 12:32 GMT, martin wrote:
> Thanks for writing back (everyone). I'm so new to unix and terminal
> that i haven't yet figured out how to do two things -(among about a
> million other things
> one - type multi line commands into the terminal w/out terminal wanting
> to process the first line after hitting return... or setting up a code
> file for terminal to fetch to collect statements to run
> and, two - how to just type the code you wrote above on one line using
> ";" to seperate each command.
>
> since i think it'll be easier to put it all in one line (as i'm going
> to have to have applescript send that line to terminal) could you
> possibly re-type what you wrote above, and show me the format for doing
> it all in one command line? when i tried last night, i kept getting
> errors about how the ( ) were in the wrong place - (some examples i'd
> seen used curly braces and ( ) and i was trying to follow that
> syntax...)
>
> i would really appreciate being able to see both side-by-side.
> thanks so much!
First, please quote relevant material.
What do you want converted to a single line? As a rule of thumb,
where there was a new line, place a semi-colon. If that doesn't
work, show us exactly what you tried (cut and paste; do not
retype) along with the exact error message, if any.
Note that braces { } need to be separated by spaces, and the
closing brace preceded by a semi-colon is it's all on one line:
{ echo A; read B; }
--
Chris F.A. Johnson http://cfaj.freeshell.org/shell
========================================
===========================
My code (if any) in this post is copyright 2005, Chris F.A. Johnson
and may be copied under the terms of the GNU General Public License
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| martin 2005-02-07, 8:47 pm |
| sorry about that... when i get home in this afternoon, i'll try it out
- and then i'll be able to cut/paste with my question again by
mid-afternoon.
thanks.
martin
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| martin 2005-02-07, 8:47 pm |
| ok, i tried to format code from your example into a single line string
of command statements...
the first time, i included the "> /dev/null/" portion, which i have no
idea what it means or causes to happen... here's the cut/paste of the
command exactly as i entered it... and, following that, the error
output from terminal.
../alan 3build6.alan >newtestoutput.txt ; if grep "No warnings"
newtestoutput.txt > /dev/null/ ; then ; ./arun 3build6 ; else ; printf
"bad compile, check file\n" ; end if ;
/dev/null/: Not a directory.
so i removed the dev/null/ portion and tried again, this time with a
different error.
../alan 3build6.alan >newtestoutput.txt; if grep "No warnings or errors
detected" newtestoutput.txt; then; ./arun 3build6; else; printf "bad
compile\n"; end if;
result: if: Expression Syntax.
note: the compile Was a success - the newtestoutput file Was
generated... but i don't believe that text string was compared in
either version before the error msg was triggered. i see what you
meant about simplifying - but in this case, i absolutly must have some
sort of string comparision to active the IF/ELSE statements.
also - if you have time, please briefly tell me what dev/null/ is for.
(btw, my computer is mac osx 2.8)
thank you
martin
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| Ed Morton 2005-02-07, 8:47 pm |
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martin wrote:
> ok, i tried to format code from your example into a single line string
> of command statements...
> the first time, i included the "> /dev/null/" portion, which i have no
> idea what it means or causes to happen... here's the cut/paste of the
> command exactly as i entered it... and, following that, the error
> output from terminal.
>
> ./alan 3build6.alan >newtestoutput.txt ; if grep "No warnings"
> newtestoutput.txt > /dev/null/ ; then ; ./arun 3build6 ; else ; printf
> "bad compile, check file\n" ; end if ;
>
> /dev/null/: Not a directory.
There's no "/" at the end of "/dev/null". See the original post.
> so i removed the dev/null/ portion and tried again, this time with a
> different error.
>
> ./alan 3build6.alan >newtestoutput.txt; if grep "No warnings or errors
> detected" newtestoutput.txt; then; ./arun 3build6; else; printf "bad
> compile\n"; end if;
There's no space between "end" and "if" in the original post, but it
actually should be "fi" instead.
Please use newlines and other white-space when posting code segments -
it'll make spotting problems a lot easier.
Also, include the relevant section of the post you're responding to
since it's not always obvious.
> result: if: Expression Syntax.
>
> note: the compile Was a success - the newtestoutput file Was
> generated... but i don't believe that text string was compared in
> either version before the error msg was triggered. i see what you
> meant about simplifying - but in this case, i absolutly must have some
> sort of string comparision to active the IF/ELSE statements.
Not from what you've posted so far.
> also - if you have time, please briefly tell me what dev/null/ is for.
> (btw, my computer is mac osx 2.8)
/dev/null is just a garbage can to send output to that you don't want to
see.
Ed.
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| martin 2005-02-08, 8:01 am |
| thank you! you were right - those little changes got my code a'working
sorry the statements were tough to read, but i wanted to write it on a
single line just to make sure i was doing it correctly (new to this, ya
know ;^)
thanks again
martin
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