I am writing a bash script to store the individual values of minutes and seconds.
However, I am unable to do so.
TIMEFORMAT='%3lR'
exec 3>&1 4>&2
cmd='ls -l / >/dev/null 2>&1'
var=$( { time $cmd 1>&3 2>&4; } 2>&1 ) # Captures time only.
exec 3>&- 4>&-
echo 'Get the var'
echo $var
min=$(echo $var | awk -F 'm|s' '{print $2}')
echo $min
The output shows ls -l / which I don't want.
Next, I don't understand what is exec 3>&- 4>&-. I copied this from other stack overflow answers. I don't understand what is the use of { inside the ( bracket.
Try this:
TIMEFORMAT='%3lR'
var=$({ time ls -l / 2>&1 > /dev/null; } 2>&1)
echo 'Get the var'
echo ${var}
min=$(echo ${var} | awk -F 'm|s' '{print $2}')
echo ${min}
Related
I try to run the following command (ref.) using nohup, which basically separates stdout and stderr into two processes.
{ foo 2>&1 1>&3 3>&- | sed -u 's/^/err: /'; } 3>&1 1>&2 | sed -u 's/^/out: /'
The foo script is like below.
#!/bin/bash
while true; do
echo a
echo b >&2
sleep 1
done
This is the test result.
$ nohup { foo 2>&1 1>&3 3>&- | sed -u 's/^/err: /'; } 3>&1 1>&2 | sed -u 's/^/out: /' >/dev/null 2>&1 &
-bash: syntax error near unexpected token `}'
That's syntatically impossible. But you can wrap your {} in a sh -c cmd:
nohup sh -c 'foo 2>&1 1>&3 3>&- | sed -u "s/^/err: /"'
Notice I change the single quote for sed to double quote.
How to print output from a loop which is piped to some other command:
for f in "${!myList[#]}"; do
echo $f > /dev/stdout # echoed to stdout, how to?
unzip -qqc $f # piped to awk script
done | awk -f script.awk
You can use /dev/stderr or second file descriptor:
echo something >&2 | grep nothing
echo something >/dev/stderr | grep nothing
You can use another file descriptor that will be connected to stdout:
# for a single command group
{ echo something >&3 | grep nothing; } 3>&1
# or for everywhere
exec 3>&1
echo something >&3 | grep nothing
# same as above with named file descriptor
exec {LOG}>&1
echo 123 >&$LOG | grep nothing
You can also redirect the output to current controlling terminal /dev/tty (if there is one):
echo something >/dev/tty | grep nothing
I have a bash script like this:
#!/bin/bash
log_file=/home/michael/bash/test.log
checkalive=checkalive.php
#declare
needRestart=0
#Check checkalive.php
is_checkalive=`ps aux | grep -v grep| grep -v "$0" | grep $checkalive| wc -l | awk '{print $1}'`
if [ $is_checkalive != "0" ] ;
then
checkaliveId=$(ps -ef | grep $checkalive | grep -v 'grep' | awk '{ printf $2 }')
echo "Service $checkalive is running. $checkaliveId"
else
echo "$checkalive OFF"
needRestart=1
fi
#NEED needRestart
if [ $needRestart == "1" ];
then
#START SERVICE
echo "Restarting services..."
/usr/bin/php5.6 /home/michael/bash/$checkalive >/dev/null 2>&1 &
echo "$checkalive..."
echo `date '+%Y-%m-%d %H:%M:%S'` " Start /home/michael/bash/$checkalive" >> $log_file
fi
I can run it manually but when I try to run it in Cron, it doesn't work for some reasons. Apparently the command:
/usr/bin/php5.6 /home/michael/bash/$checkalive >/dev/null 2>&1 &
does not work.
All of file permissions are already set to executable. Any advice?
Thank you
You have run into one of cron's most common mistakes, trying to use it like an arbitrary shell script. Cron is not a shell script and you can't do everything you can do in one, like dereferencing variables or setting arbitrary new variables.
I suggest you replace your values into the cron line and avoid usage of variables
/usr/bin/php5.6 /home/michael/bash/checkalive.php >/dev/null 2>&1 &
Also, consider removing the trailing & as it is not necessary.
There are a few layers here, so bear with me.
My docker-container ssh -c"echo 'YAY!'; exit 25;" command executes echo 'YAY!'; exit 25; in my docker container. It returns:
YAY
error: message=YAY!
, code=25
I need to know if the command within the container was successful, so I append the following to the command:
docker-container ssh -c"echo 'YAY!'; exit 25;" >&1 2>/tmp/stderr; cat /tmp/stderr | grep 'code=' | cut -d'=' -f2 | { read exitStatus; echo $exitStatus; }
This sends the stderr to /tmp/stderr and, with the echo $exitStatus returns:
YAY!
25
So, this is exactly what I want. I want the $exitStatus saved to a variable. My problem is, I am placing this into a bash script (GIT pre-commit) and when this exact code is executed, the exit status is null.
Here is my bash script:
# .git/hooks/pre-commit
if [ -z ${DOCKER_MOUNT+x} ];
then
docker-container ssh -c"echo 'YAY!'; exit 25;" >&1 2>/tmp/stderr; cat /tmp/stderr | grep 'code=' | cut -d'=' -f2 | { read exitStatus; echo $exitStatus; }
exit $exitStatus;
else
echo "Container detected!"
fi;
That's because you're setting the variable in a pipeline. Each command in the pipeline is run in a subshell, and when the subshell exits the variable are no longer available.
bash allows you to run the pipeline's last command in the current shell, but you also have to turn off job control
An example
# default bash
$ echo foo | { read x; echo x=$x; } ; echo x=$x
x=foo
x=
# with "lastpipe" configuration
$ set +m; shopt -s lastpipe
$ echo foo | { read x; echo x=$x; } ; echo x=$x
x=foo
x=foo
Add set +m; shopt -s lastpipe to your script and you should be good.
And as Charles comments, there are more efficient ways to do it. Like this:
source <(docker-container ssh -c "echo 'YAY!'; exit 25;" 2>&1 1>/dev/null | awk -F= '/code=/ {print "exitStatus=" $2}')
echo $exitStatus
i need to redirect stout and stderr in bash each to separate file.
well i completed this command:
((/usr/bin/java -jar /opt/SEOC2/seoc2.jar 2>&1 1>&3 | tee --append /opt/SEOC2/log/err.log) 3>&1 1>&2 | tee --append /opt/SEOC2/log/app.log) >> /opt/SEOC2/log/combined.log 2>&1 &
which works fine running from a command line.
trying to put the very same command into bash script
...
12 cmd="(($run -jar $cmd 2>&1 1>&3 | tee --append $err) 3>&1 1>&2 | tee --append $log) >> $combined 2>&1"
...
30 echo -e "Starting servis..."
31 $cmd &
32 pid=`ps -eo pid,args | grep seoc2.jar | grep -v grep | cut -c1-6`
33 if [ ! -z $pid ]; then
...
leads to error like this:
root#operator:/opt/SEOC2# seoc2 start
Starting servis...
/usr/local/bin/seoc2: line 31: ((/usr/bin/java: dir or file doesn't exist
tried to cover this command by $( ), ` ` etc but with no effect at all :(
any suggestion or advice would be very appreciated, playing around for hours already :/
thanx a lot
Rene
If you store the whole command line in a variable you have to use eval to execute it:
cmd="(($run -jar $cmd 2>&1 1>&3 | tee --append $err) 3>&1 1>&2 | tee --append $log) >> $combined 2>&1"
...
eval $cmd &