I have a line working from this thread that tails a file until a matching pattern is found. It works well, but I can't find a way to suppress the output that occurs afterwards.
The line is:
sh -c 'tail -n +0 -f $logfile | { sed "/EOF/ q" && kill $$ ;}'
piping to /dev/null doesn't work as I don't get any output at all from the tail command that way. Also, I'm on OSX and various other sed and awk suggestions don't work due to the syntax.
It always finishes with the below, instead of nothing:
sh: line 10: 14285 Terminated: 15 sh -c 'tail -n +0 -f $logfile | { sed "/EOF/ q" && kill $$ ;}'
I'd also like not to display the matched text (EOF in the above example).
Any suggestions welcomed.
for a file (log for example)
sed -u "/pattern/ q" YourFile
for a pipe
ls -l | sed -u "/pattern/ q"
the -u of sed tell it to work as a stream input
It's the shell's job monitoring popping the message.
nomonitor() {
set +m
"$#"
set -m
}
nomonitor sh -c 'tail -n +0 -f $logfile | { sed "/EOF/ q" && kill $$; }'
You can actually discard the stderr like this:
sh -c 'tail -n +0 -f $logfile | { sed "/EOF/q" && p=$$ && kill $((p+1)) ; }'
Related
I have a bash function
agg_generror () {
echo $1
find ${folder} -name "${prefix}_*_${1}_${suffix}.count" | xargs -I % sh -c 'cat %; echo "";' | awk 'BEGIN{e=0;t=0} {e+=$1;t+=$2} END{print e/t}' > generror_${1}
}
which if I call directly
agg_generror 17.5
works and doesn't complain.
But if I do
echo 17.5 | xargs -I % sh -c 'agg_generror %'
It fails with
17.5
awk: fatal: division by zero attempted
Why may the behaviour different in the two cases?
while read; do agg_generror $REPLY; done < input.txt
Basic example:
#!/bin/bash
set -e
set -x
NUM_LINES=$(printf "Hello\nHi" | grep -c "How$")
echo "Number of lines: ${NUM_LINES}" # never prints 0
Output:
++ grep -c 'How$'
++ printf 'Hello\nHi'
+ NUM_LINES=0
If there are matches, it prints the correct number of lines. Also grep "How$" | wc -l works instead of using grep -c "How$".
You can suppress grep's exit code by running : when it "fails". : always succeeds.
NUM_LINES=$(printf "Hello\nHi" | grep -c "How$" || :)
I’m using Amazon Linux with bash shell. In my bash script, how do I construct a while loop that will spin so long as the command
tail -10 /usr/java/jboss/standalone/log/server.log
does not contain the string “FrameworkServlet ‘myprojectDispatcher': initialization completed”?
You can use:
tail -n 10 -f /usr/java/jboss/standalone/log/server.log |
awk '/FrameworkServlet.*myprojectDispatcher.*initialization completed/{exit} 1'
awk will exit when it encounters search string otherwise it will keep writing input to stdout.
However do keep in mind that the tail command is buffered and to avoid that behavior try stdbuf gnu utility:
stdbuf -i0 -o0 -e0 tail -n 10 -f /usr/java/jboss/standalone/log/server.log |
awk '/FrameworkServlet.*myprojectDispatcher.*initialization completed/{exit} 1'
I can try this:
#!/bin/bash
MATCH="FrameworkServlet ‘myprojectDispatcher': initialization completed"
while :
do
if tail /usr/java/jboss/standalone/log/server.log | grep -q "$MATCH"; then
exit 0
else
sleep 1
fi
done
while [ -nz grep -q "FrameworkServlet ‘myprojectDispatcher': initialization completed" /usr/java/jboss/standalone/log/server.log ]; do
# wait a second
sleep 1
done
# do the stuff
echo "we got it!"
Ok so I have the following script that updates Route43 DNS entries. Unfortunately there is a limit to the number of calls per second you can make so I need to make the final Xargs command sleep for about a second between each iteration.
I've tried a couple of things like ' {../cli53 blah; sleep 10; } ' and I cant seem to get it to work. Does anyone have any suggestions please:
#!/bin/bash
set root='dirname $0'
ec2-describe-instances -O ******* -W ******* --region eu-west-1 |
perl -ne '/^INSTANCE\s+(i-\S+).*?(\S+\.amazonaws\.com)/
and do { $dns = $2; print "$1 $dns\n" }; /^TAG.+\sName\s+(\S+)/
and print "$1 $dns\n"' |
perl -ane 'print "$F[0] CNAME $F[1] --replace\n"' |
grep -v 'i-' | xargs --verbose -n 4 /usr/local/bin/cli53 rrcreate -x 5 contoso.com
Edit: Thanks Etan for the Answer. Here is my solution for anyone else that needs it:
I had to include the -I %variable% switch into the xargs statement aswel to make sure that the feed in was passed as parameters to cli53 but it all looks to be working nicely now.
#!/bin/bash
set root='dirname $0'
ec2-describe-instances -O ******* -W ******* --region eu-west-1 |
perl -ne '/^INSTANCE\s+(i-\S+).*?(\S+\.amazonaws\.com)/
and do { $dns = $2; print "$1 $dns\n" }; /^TAG.+\sName\s+(\S+)/
and print "$1 $dns\n"' |
perl -ane 'print "$F[0] CNAME $F[1] --replace\n"' |
grep -v '^i-' |
xargs --verbose -n 4 -I myvar /bin/sh -c '{ /usr/local/bin/cli53 rrcreate -x 5 contoso.com 'myvar'; sleep 1; printf "\n\n"; }'
The simplest solution would be to simply put the cli53 and sleep calls in a script and use xargs to execute the script.
If you don't want to do that you should be able to do what you were trying to do with this:
... | xargs ... /bin/sh -c '{ /usr/local/bin/cli53 ... "$#"; sleep 10; }' -
This is my bash script:
#!/usr/local/bin/bash -x
touch /usr/local/p
touch /usr/local/rec
DATA_FULL=`date +%Y.%m.%d.%H`
CHECK=`netstat -an | grep ESTAB | egrep '(13001|13002|13003|13004|13061|13099|16001|16002|16003|16004|16061|16099|18001|18002|18003|18004|18061|18099|20001|20002|20003|20004|20061|20099|13000|16000|18000|20000)' | awk '{ print $5 }' | sort -u | wc -l`
netstat -an | grep ESTAB | egrep '(13001|13002|13003|13004|13061|13099|16001|16002|16003|16004|16061|16099|18001|18002|18003|18004|18061|18099|20001|20002|20003|20004|20061|20099|13000|16000|18000|20000)' | awk '{ print $5 }' | sort -u | wc -l > /usr/local/www/p
STAT=`cat /usr/local/www/rec`
if [ "$CHECK" -gt "$STAT" ]; then
echo $CHECK"\n"$DATA_FULL > /usr/local/p
fi
Ofcourse I've runned chmod +x script.sh and then sh script.sh, then I receive the following message: [: : bad number.
Why does it happends?
Run your script using
sh -x script.sh
It'll print every line it executes and the variable output.
Run the netstat command and stat command outside and check.
If these are integer for sure, use this syntax,
if [ "0$(echo $CHECK|tr -d ' ')" -gt "0$(echo $STAT|tr -d ' ')" ];
A simple hack. Only works if $STAT is always either empty or positive number.
Are you sure that both STAT and CHECK are numbers that can be compared with -gt?
probably your /usr/local/www/rec is empty. Try
STAT=`cat /usr/local/www/rec 2>/dev/null || echo 0`
maybe.