Script to extract text from one file to another

rlagreid · 04-22-2013, 06:57 AM

Hi,

I need a script to extract and reformat some text from one file into another.
I am a total newbie and need proper, detailed descriptions.

The file I have looks like this:

22-04-13, 1055
TempIn 24
TempEx 14
WindHi 5
WindAv 5
WindDr 90
BarmPs 29825
HumdIn 27
HumdEx 49
RnFall 0.00
DailyRnFall 0.28

...and the output I need looks like this:

outsideTemp=14
insideTemp=24

I need to have this script running at 10 minute intervals.
Thanks in advance.

Sigg3.net · 04-22-2013, 08:53 AM

You can easily do that with sed substitute:

Code:

sed 's/foo/bar/g'

sed is the program, s stands for substitute, /foo/ is the search query and bar/ its replacement. Example:

Code:

sed 's/TempIn /insideTemp=/g'

Will substitute TempIn with insideTemp=. Notice the space after TempIn to substitute that as well.

Are you going to store or just display this info? Sed does this "on the fly" more or less (not humanly visible).

For a file testfile do:

Code:

cat testfile | sed 's/TempIn /insideTemp=/g'

to output the new line "live".

Otherwise you'll need 2 files: inputfile and outputfile

Code:

#!/bin/bash
inputfile="/path/to/inputfile"
outputfile="/path/to/outputfile"

# in case output file does not exist
touch -a $outputfile

cat testfile | sed 's/TempIn /insideTemp=/g' >> $outputfile

Repeat for each line. The double >> just appends and does not replace text. If you want to use 2 files and display the latter, you'll need to empty or just delete the outputfile on consecutive runs;

Code:

#!/bin/bash
inputfile="/path/to/inputfile"
outputfile="/path/to/outputfile"

# if outputfile exists delete it, else touch/create it
if [ -f $outputfile ] ; then
	rm $outputfile
else
	touch -a $outputfile
fi

# substitutions:
cat testfile | sed 's/TempIn /insideTemp=/g' >> $outputfile

# fill in the rest above, then
exit

Then you'll need to save this as something.sh, chmod +x something.sh to make it executable (like a program), and then ask cron to run this at your desired interval.

rlagreid · 04-22-2013, 09:22 AM

Thanks.
It moves me in the right direction, but I need to replace the first line which is changing for every run, with a blank line and remove the lines following the TempEx line.

david1941 · 04-22-2013, 09:36 AM

try this sed pipe

sed 's/TempIn/insideTemp=/g; s/TempEx/outsideTemp=/g ' <infile |grep 'Temp' >outfile

Sigg3.net · 04-22-2013, 09:39 AM

Okay. Instead of trimming away individual lines (you could do that with tail -n +2 "$FILE"), do a grep to select the lines you DO want.

Code:

#!/bin/bash
inputfile="/path/to/inputfile"
outputfile="/path/to/outputfile"

# if outputfile exists delete it, else touch/create it
if [ -f $outputfile ] ; then
	rm $outputfile
else
	touch -a $outputfile
fi

# substitutions:
cat testfile | grep "TempIn" | sed 's/TempIn /insideTemp=/g' >> $outputfile
cat testfile | grep "TempEx" | sed 's/TempEx /outsideTemp=/g' >> $outputfile

exit

grep "TempIn" will grep (or grip) the whole line of text, THEN pipe this line to sed..
You can also use tr (translate) instead of sed, but I'm much more comfortable with the latter

rlagreid · 04-22-2013, 09:46 AM

Thank you so much.

My problem is solved :-)

Sigg3.net · 04-22-2013, 10:05 AM

No problem

I advise you to play around in bash as much as you can. It can make GNU/Linux so much easier and fun!

David the H. · 04-23-2013, 10:25 AM

Code:

sed -n '/TempIn/ s/TempIn /insideTemp=/p ; /TempEx/ s/TempEx /outsideTemp=/p' infile.txt

-n suppresses output by default, and the 'p' modifier to the substitution command prints out only the lines that get modified. The output of the two lines will in the order they appear in the input, however. If you really need to reverse them it's a bit more complex.

Code:

sed -n '/TempIn/ { s/TempIn /insideTemp=/; h} ; /TempEx/ s/TempEx /outsideTemp=/p; $ { g ;p }' infile.txt

The "h" command moves the modified "TempIn" line into the hold buffer for later use. Then the "TempEx" substitution is made and printed. When it reaches the last line, it gets the contents of the hold buffer and prints it.

Here are a few useful sed references:
http://www.grymoire.com/Unix/Sed.html
http://sed.sourceforge.net/grabbag/
http://sed.sourceforge.net/sedfaq.html
http://sed.sourceforge.net/sed1line.txt
http://www.catonmat.net/series/sed-one-liners-explained

Sigg3.net · 04-24-2013, 12:45 PM

Nice!