i'm a relative newbie to unix (i'm on OSX) and i have a specific problem i'm tripped up on:

i'm piping the output of top (in log format) into an awk command which formats the information (and eventually will send it out continuously via udp/osc to another app). my problem is with what comes up in the terminal when i try running top -l1000 | awk -f filterfile. the samples pop up two at a time! i need for them to be at relatively constant intervals for this application. does anyone know why this might be happening? i've included my (simple and kludgy) awk file below. thanks in advance for any help.


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$1 !~ /Processes:|Load|SharedLibs:|MemRegions:|PhysMem:|VM:|PID/ && $2 !~ /Window|AOL|awk|top|tcsh|login|lookupd|AppleSpell|iChatAgent|UniversalA|SystemUISe|pbs|DirectoryS|log inwindo|NortonMiss|cron|cupsd|inetd|automount|nfsiod|coreservic|netinfod|crashrepor|mDNSRespon|syslo gd|autodiskmo|NortonAuto|ATSServer|SecuritySe|configd|dynamic_pa|update|kextd|mach_init|init|kernel_ tas|fix_prebin|Norton|NortonMiss|SecurityAg|SETI@home_|SETI@homeI|S@hScreenS|System|CPU|Internet|DVD |Audio|Echo24|SuperColli|scsynth|MaxMSP|MIDIServer|Image|Key|Burning|Sloppy|Adobe/ { print $2, $3, $5, $6, $7 }
$2 ~ /Window|AOL/ { print $2$3, $4, $6, $7, $8 }
$2 ~ /MaxMSP/ { print $2, $4, $6, $7, $8 }
$2 ~ /Norton|Image|System|CPU|Internet|DVD|Audio|Echo24|Key|Burning|Sloppy|Adobe/ && $3 ~ /Caps|Ant|Pre|Capt|Monito|E|Player|Hija|Con|Mo|Sok|Phot/ { print $2$3, $4, $6, $7, $8 }

A reasonable guess would be buffering. A program like top may change its buffering stragety based on the output file. I don'y use OSX. Does your cat command have -u? If so try

top -l1000 | cat -u

I'll bet you get a similiar result.

my cat does have -u but it's doin some odd things here. really doesn't change the way anything looks.

"top -l4 -s1" posts 1 sample a second.

"top -l4 -s1 | cat -u" posts 2 samples every 2 seconds.

"top -l4 -s1 | awk -f myfile" still posts 2 samples every 2 seconds.

oddly enough, adding cat -u to the end of my command causes it to wait until all of the samples have gone through before it posts anything. so "top -l4 -s1 | awk -f myfile | cat -u" waits four seconds and then posts all four samples at once.

it's interesting to see these differences. a little frustrating too, but interesting. =) could this be some buffering in the pipe?

The point of trying the "cat -u" instead of your awk script was to show that it's not the awk script. The top command is buffering the output.

i wound up making a script that just loops the command for each sample. works well enough.

thanks for your help!