shell scripts and varibales

allycavs · 12-04-2004, 06:26 AM

Hi i wanna do something very easy. something like this.

num='grep -w "+ 4 0" out.txt | awk '{print $4;}''

basically i want to pass the output of this to num. and as it is awk prints to the screen. can i stop awk printingin its output to thje screen. i think what i want to do involves getline aswell but i cant seem to get this write.

also to finish off once i have num how could i append num to another file called 1.txt. when i say append i mean stick it on at the end. this is basic i know but im struggling to do it. this is a simplified version of what im doing but i should be able to do what i want to do if i get an answer here.

cheers,
Alan

zulfilee · 12-04-2004, 08:31 AM

num=`grep -w "+ 4 0" out.txt | awk '{print $4;}'`
echo $num >> 1.txt

So its backtick not single quotes there .

And awk will not print it to screen

Cheers
Z

wmakowski · 12-04-2004, 09:24 AM

Use I/O redirection to send output to a file rather than standard out. If you want all the output from your script to go to a file you would type scriptname > outfile at the command line. The > sign redirects the output to the file outfile. To append output to a file use >>.

You can also use this technique inside your script to direct output to multiple files. For example, if I wanted a logfile with execution status and an output file my script might look something like.

Code:

#!/bin/bash
#
# Writing to files example
#

SUCCESS="success."
FAILURE="failure."

ps -aux > out.txt
let rs=$?
printf "Job was a " > log.txt
	
if [ $rs = 0 ]
then
   printf "%s\n" $SUCCESS >> log.txt
else
   printf "%s\n" $FAILURE >> log.txt
fi

Bill

allycavs · 12-04-2004, 09:25 AM

Thanks zulfilee
im nearly finsihed my script now. just one more thing if you dont mind

if i want to do the following

echo ("$ns at" & $time & "$udp1 send [CONST_SIP_SIZE]") >> UDP.tcl
echo "$ns at [CONST_FINISH_TIME] "FINISH"" >> UDP.tcl
echo "$ns run" >> UDP.tcl

where ns is not a variable but the actual text i want to append. time is a variable and $udp is not a variable but actual text. and i want FINISH to be "FINISH" in UDP.tcl

hk_linux · 12-08-2004, 08:00 AM

echo ("$ns at" & $time & \"\$udp1 send [CONST_SIP_SIZE]") >> UDP.tcl
echo "$ns at [CONST_FINISH_TIME] \"FINISH\"" >> UDP.tcl
echo "$ns run" >> UDP.tcl

\ is the escape charater you gotta use