maxmax20 <[email protected]> wrote:
> rrdtool update /home/pi/net/net.rrd N:'cut -d, /home/pi/net/devices.csv -f13
> | cut -d: -f2'::::: to get the first value out of the csv file, but it seems
> that it won't work.
As suggested, put echo in front of it - and possibly pipe the output through
hexdump.
One thought, does the SCV file contain exactly one line - not zero lines, not 2
lines (having one line and a newline counts as 2 lines). You may want to add
"head -1"
If working in bash, you can cut things down somewhat by using Bash builtin
string functions - one some of my data collection scripts, it's made a huge
difference. When you use cut you are spawning two new processes (three is you
add head as well).
Check the man page for parameter expansion, specifically the ${parameter#word},
${parameter##word}, ${parameter%word}, and ${parameter%%word} forms. I think
this will get you your value :
# Get the file
Utmp=$( < /home/pi/net/devices.csv )
# Get everything after the 12th ','
Utmp=$(Utmp#*,*,*,*,*,*,*,*,*,*,*,*,)
# Get everything after the first ':'
Utmp=$(Utmp#*:)
# Optional - depends on your file, delete everything after the next , or :
Utmp=$(Utmp%%,*) or Utmp=$(Utmp%%:*)
Don't think it applies here (though I don't know if fiddling with IFS might
help), but another trick you could try is using arrays. My specific action was
getting traffic counts from an interface, so I have a script with :
Utmp=$(< /proc/net/dev)
Utmp=(${Utmp#*ethext:})
UpdateVal=${Utmp[0]}:${Utmp[8]}
I'll leave you to figure it out.
PS - no I didn't come up with this myself, someone else pointed me in that
direction.
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