[SOLVED] gawk printf array

haraldboehmecke · 01-29-2012, 07:38 AM

Hi guys,

got stuck on this one:

Code:

gawk 'BEGIN {
printf("|%20s|%50s|%20s|\n","Value","Master","Slave");
printf("|%20s|%50s|%20s|\n","Instance", ENVIRON["${MVRRP_INSTANCE[0]}"] ,"sinst");
}'

outputs:

Code:

|               Value|                                            Master|               Slave|
|            Instance|                                                  |               sinst|

array is not being printed. Why?

tried the following printf commands with no luck:

Code:

printf("|%20s|%50s|%20s|\n","Instance",ENVIRON["${MVRRP_INSTANCE[0]}"],"sinst");
printf("|%20s|%50s|%20s|\n","Instance","${MVRRP_INSTANCE[0]}","sinst");
printf("|%20s|%50s|%20s|\n","Instance",${MVRRP_INSTANCE[0]},"sinst");
printf("|%20s|%50s|%20s|\n","Instance",`eval echo ${MVRRP_INSTANCE[0]}`,"sinst");
printf("|%20s|%50s|%20s|\n","Instance","`eval echo ${MVRRP_INSTANCE[0]}`","sinst");

Thanks for your efforts

grail · 01-29-2012, 08:02 AM

Well I guess my question to you would be, where is this variable / array being set? How would you access this value at the command line?

David the H. · 01-29-2012, 08:49 AM

I'm assuming that "${MVRRP_INSTANCE[0]}" is a shell array entry, correct?

Shell variable values need to either be imported into awk variables, or else careful quoting must be used to allow them to expand before the awk command runs. As it stands, the entire gawk expression is enclosed in single-quotes, and no expansions are done.

Read up on the basics here:

http://www.grymoire.com/Unix/Awk.html#uh-4
http://www.gnu.org/software/gawk/man...hell-Variables

Edit: It appears that you're trying to use the ENVIRON array to fetch the value from the current environment. In which case your problem is probably that the shell value needs to be exported in the parent shell first, so that it gets copied to the environment of the gawk sub-process.

But why are you using gawk just to (apparently) print a simple formatted header? Unless you intend to expand the command later to process some kind of input, why not use your shell's built-in printf instead?

Code:

printf "|%20s|%50s|%20s|\n" Value Master Slave
printf "|%20s|%50s|%20s|\n" Instance "${MVRRP_INSTANCE[0]}" sinst

PTrenholme · 01-29-2012, 03:41 PM

Try "echo ${MVRRP_INSTANCE[0]}" | getline MVRRP;, and use the MMRRP variable in your printf statement. (Technically, you should close the pipe, but it will be automatically closed when the gawk program finishes, so it's probably not necessary.)

haraldboehmecke · 02-01-2012, 04:21 AM

thanks to your help I found a solution. The next time I will mention that I am working on a BASH script

KR,

Harald

grail · 02-01-2012, 05:46 AM

Remember to provide your solutions so others can learn from you