I've got a redirect dilemma that I can't get past in a bash backup script I'm developing in CentOS 6.4. I want to redirect all output to two separate files: one tmp and one permanent. The script loops through an external source list and I'd like for the tmp log files to be specific to the source, so that I can send an email if that specific source had errors containing that log (and conversely remove the tmp if the backup completes without error).
I'm using exec to tee my output:
exec > >(tee -a ${templog} /var/log/rob/rob.log) 2>&1
This works if I place at the top of the script, but here the variable isn't defined yet, so I can't do source-specific logs.
If I place this within the while loop, it grabs the variable, but writes a copy of each line determined by the total iterations of the loop; for the example below, I have four sources it iterates through, so I get output for each source in quadruplicate:
-S-07/11/14 09:15:35 ROB-Source Process for cc2-gamma has started-S-
-S-07/11/14 09:15:35 ROB-Source Process for cc2-gamma has started-S-
-S-07/11/14 09:15:35 ROB-Source Process for cc2-gamma has started-S-
-S-07/11/14 09:15:35 ROB-Source Process for cc2-gamma has started-S-
Share cc2-gamma is not Mounted. Try 1 of 5 to mount...
Share cc2-gamma is not Mounted. Try 1 of 5 to mount...
Share cc2-gamma is not Mounted. Try 1 of 5 to mount...
Share cc2-gamma is not Mounted. Try 1 of 5 to mount...
Is there a different way to tee the output within the loop to prevent this (without touching each line of course)? Or is there something rotten in my loops that I'm not seeing? Here's the whole script. Please excuse the mess and style.. I'm clearly not finished. I didn't include the config.conf and backup source file as they don't affect the output. Let me know if needed. Thanks.
#!/bin/bash
#V.2014.0723 - Radation Oncology Backup script
#declarations
SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/rob
source /rob/conf/config.conf
while read smbdir 'smbpath' exclfile drive foldername; do
#loop declarations
mountedfile=/rob/${smbdir}.MOUNTED
runningfile=/rob/${smbdir}.RUNNING
lastrunfile=/rob/${smbdir}_${foldername}.LASTRUN
templog=/rob/${smbdir}_${foldername}.TMPLOG
errorfile=/rob/${smbdir}_${foldername}.HAD_ERRORS
backupfile=/rob/${baname:0:3}_rtbackup.sql.bz2 # for the -l seccton below -- sql backup of backup.sql
#exec > >(tee -a ${templog} /var/log/rob/rob.log) 2>&1
### SOURCE BACKUP ##############################################################################################
if [ "$1" == "-s" ]
then
exec > >(tee -a /var/log/rob/rob.log ${templog}) 2>&1
#Write Source STDOUT and STDERR to both permanent and temporary log file. Must be in loop to use variables.
#exec > >(tee -a ${templog} /var/log/rob/rob.log) 2>&1
#exec > >(tee -a /var/log/rob.log ${templog}) 2>
if [ "${sources_active}" == "1" ]
then
echo "-S-$(date "+%m/%d/%y %T") ROB-Source Process for $smbdir has started-S-"
# unmount all cifs shares, due to duplicate mounts, write file to prevent concurrentcy
umount -a -t cifs > /dev/null
# The following will test to see if the souce is mounted, and if not, mount it.
for i in {1..5}
do
if mountpoint -q /mnt/${smbdir}/${drive}/${foldername}
then
echo "Share ${smbdir} is Mounted."
touch $mountedfile
break
else
sleep 2
echo "Share ${smbdir} is not Mounted. Try $i of 5 to mount..."
mkdir -p /mnt/${smbdir}/${drive}/${foldername} > /dev/null
mount -t cifs ${smbpath} -o ro,username=<USER>,password=<PW>,workgroup=<DOMAIN> /mnt/${smbdir}/${drive}/${foldername}
fi
done
# Test to see if above was successful, and if rob is not already running, run the backup.
if [[ -f ${mountedfile}&& ! -f ${runningfile} ]]
then
src="/mnt/${smbdir}/$drive"
dst="/backup/rob/"
touch ${runningfile}
/root/bin/rtbackup -m /mnt -p ${src}/${foldername} -b ${dst} -x #${exclfile}
if [ "$?" -ne "0" ]; then
#Errors Running RTBackup
rm -f ${runningfile} > /dev/null 2>&1
rm -f ${mountedfile}> /dev/null 2>&1
echo "$(date "+%m/%d/%y %T") Source Process for ${smbdir} had errors running:-SSS"
echo "$errors" >&2
touch ${errorfile}
exit 1
else
echo "What the hell is this doing?"
fi
#NO Errors Running RTBACKUP
rm -f ${templog}
rm -f ${runningfile} > /dev/null 2>&1
rm -f ${mountedfile} > /dev/null 2>&1
echo "$(date "+%m/%d/%y %T") Source Process for ${smbdir} did not have any errors"
else
#backup will *NOT* run, cleaning up and logging
rm -f ${mountedfile} > /dev/null 2>&1
echo "$(date "+%m/%d/%y %T") ${smbdir} could not be mounted, or is already in progress. Backup could not complete."
touch ${errorfile}
tail /var/log/rob/robso.log | mail -s "ROBSO Failed to run for ${smbdir} on ${baname}" ${email}
fi
echo "-F-$(date "+%m/%d/%y %T") ROB-Source Process for ${smbdir} has finished-F-"
#break
elif [[ "${sources_active}" == "0" ]]
then
echo "***$(date "+%m/%d/%y %T") ROB-Source Process for ${smbdir} did not run because the job is not set as active***"
#break
fi
done < /rob/conf/${baname}.conf
if [ $? -eq 10 ]; then exit 0; fi
You can use curly braces to redirect a set of commands; as it says in the bash manual about command grouping, "When commands are grouped, redirections may be applied to the entire command list". It behaves more-or-less like an anonymous function.
{
command1
command2
} > >(tee -a ${templog} /var/log/rob/rob.log) 2>&1
You can do the same with a named function, too, if you're so inclined, but I don't know offhand what environment would be used to expand the redirections. (If you do, please edit this answer!)
# Untested. This MIGHT work.
your_log_command() {
command1
command2
} > >(tee -a $1 /var/log/rob/rob.log) 2>&1
your_log_command $templog
your_log_command $something_else
Related
I've been trying to understand a problem that's cropped up with some of the scripts we use at work.
To generate many of our script logs, we utilize the exec command and file redirects to print all output from the script to both the terminal and a log file. Occasionally, for information that doesn't need to be displayed to the user, we do a straight redirect to the log file.
The issue we're seeing occurs on the last line of output to the file when we're printing the number of errors that occurred during that execution: The text doesn't get printed to the file.
In an attempt to diagnose the problem, I wrote a simplified version of our production script (script1.bash) and a test script (script2.bash) to try to tease out the problem.
script1.bash
#!/bin/bash
log_name="${USER}_`date +"%Y%m%d-%H%M%S"`_${HOST}_${1}.log"
log="/tmp/${log_name}"
log_tmp="/tmp/temp_logs"
err_count=0
finish()
{
local ecode=0
if [ $# -eq 1 ]; then
ecode=${1}
fi
# This is the problem line
echo "Error Count: ${err_count}" >> "${log}"
mvlog
local success=$?
exec 1>&3 2>&4
if [ ${success} -ne 0 ]; then
echo ""
echo "WARNING: Failed to save log file to ${log_tmp}"
echo ""
ecode=$((ecode+1))
fi
exit ${ecode}
}
mvlog()
{
local ecode=1
if [ ! -d "${log_tmp}" ]; then
mkdir -p "${log_tmp}"
chmod 775 "${log_tmp}"
fi
if [ -d "${log_tmp}" ]; then
rsync -pt --bwlimit=4096 "${log}" "${log_tmp}/${log_name}" 2> /dev/null
[ $? -eq 0 ] && ecode=0
if [ ${ecode} -eq 0 ]; then
rm -f "${log}"
fi
fi
}
exec 3>&1 4>&2 >(tee "${log}") 2>&1
ecode=0
echo
echo "Some text"
echo
finish ${ecode}
script2.bash
#!/bin/bash
runs=10000
logdir="/tmp/temp_logs"
if [ -d "${logdir}" ]; then
rm -rf "${logdir}"
fi
for i in $(seq 1 ${runs}); do
echo "Conducting run #${i}/${runs}..."
${HOME}/bin/script1.bash ${i}
done
echo "Scanning logs from runs..."
total_count=`find "${logdir}" -type f -name "*.log*" | wc -l`
missing_count=`grep -L 'Error Count:' ${logdir}/*.log* | grep -c /`
echo "Number of runs performed: ${runs}"
echo "Number of log files generated: ${total_count}"
echo "Number of log files missing text: ${missing_count}"
My first test indicated roughly 1% of the time the line isn't written to the log file. I then proceeded to try several different methods of handling this line of output.
Echo and Wait
echo "Error Count: ${err_count}" >> "${log}"
wait
Alternate print method
printf "Error Count: %d\n" ${err_count} >> "${log}"
No Explicit File Redirection
echo "Error Count: ${err_count}"
Echo and Sleep
echo "Error Count: ${err_count}" >> "${log}"
sleep 0.2
Of these, #1 and #2 each had a 1% fail rate while #4 had a staggering 99% fail rate. #3 was the only methodology that had a 0% fail rate.
At this point, I'm at a loss for why this behavior is occurring, so I'm asking the gurus here for any insight.
(Note that the simple solution is to implement #3, but I want to know why this is happening.)
Without testing, this looks like a race condition between your script and tee. It's generally better to avoid multiple programs writing to the same file at the same time.
If you do insist on having multiple writers, make sure they are all in append mode, in this case by using tee -a. Appends to the local filesystem are atomic, so all writes should make it (this is not necessarily true for networked file systems).
I have a shell script that does a backup. I set this script in a cron but the problem is that the backup is heavy so it is possible to execute a second rsync before the first ends up.
I thought to launch rsync in a script and then get PID and write a file that script checks if the process exist or not (if this file exist or not).
If I put rsync in background I get the PID but I don't know how to know when rsync ends up but, if I set rsync (no background) I can't get PID before the process finish so I can't write a file whit PID.
I don't know what is the best way to "have rsync control" and know when it finish.
My script
#!/bin/bash
pidfile="/home/${USER}/.rsync_repository"
if [ -f $pidfile ];
then
echo "PID file exists " $(date +"%Y-%m-%d %H:%M:%S")
else
rsync -zrt --delete-before /repository/ /mnt/backup/repositorio/ < /dev/null &
echo $$ > $pidfile
# If I uncomment this 'rm' and rsync is running in background, the file is deleted so I can't "control" when rsync finish
# rm $pidfile
fi
Can anybody help me?!
Thanks in advance !! :)
# check to make sure script isn't still running
# if it's still running then exit this script
sScriptName="$(basename $0)"
if [ $(pidof -x ${sScriptName}| wc -w) -gt 2 ]; then
exit
fi
pidof finds the pid of a process
-x tells it to look for scripts too
${sScriptName} is just the name of the script...you can hardcode this
wc -w returns the word count by words
-gt 2 no more than one instance running (instance plus 1 for the pidof check)
if more than one instance running then exit script
Let me know if this works for you.
Test both for presence of pid file and status of the running process like this:
#!/bin/bash
pidfile="/home/${USER}/.rsync_repository"
is_running =0
if [ -f $pidfile ];
then
echo "PID file exists " $(date +"%Y-%m-%d %H:%M:%S")
previous_pid=`cat $pidfile`
is_running=`ps -ef | grep $previous_pid | wc -l`
fi
if [ $is_running -gt 0 ];
then
echo "Previous process didn't quit yet"
else
rsync -zrt --delete-before /repository/ /mnt/backup/repositorio/ < /dev/null &
echo $$ > $pidfile
fi
Hope this helps!!!
So the reason I am asking this is because I'm running two programs simultaneously that are persistent, on the child process a programm is running that requires sudo rights.
#!/bin/bash
echo "Name the file:"
read filename
while [[ 1 -lt 2 ]]
do
if [ -f /home/max/dump/$filename.eth ]; then
echo "File already exist."
read filename
else
break
fi
done
#Now calling a new terminal for dumping
gnome-terminal --title="tcpdump" -e "sh /home/max/dump/dump.sh $filename.eth"
ping -c 1 0 > /dev/null **Waiting for tcpdump to create file**
#Packet analysis program is being executed
Script dump.sh
#!/bin/bash
filename=$1
echo password | sudo tcpdump -i 2 -s 60000 -w /home/max/dump/$filename -U
host 192.168.3.2
#Sudo still asks me for my password though password is piped into stdin
So I am writing a bash script which will run through all of the process ids in /proc/[pid] and read the executable that was used to run it.
From what I have had a looked at, the /proc filesystem contains the /proc/[pid]/exe symbolic link. Within the bash script I am trying work out how to read the value of "readlink /proc/[pid]/exe" to check if (deleted) or nothing is returned to find out whether the original executable exists on the disk or not.
Is there a way of doing this, so far I have?
#!/bin/bash
pid = "0"
while [ $pid -lt 32769 ]
do
if [-d /proc/$pid]; then
if [-f /proc/$pid/exe]; then
echo $pid
readlink /proc/$pid/exe
fi
fi
pid = $[$pid+1]
done
This fails to work and always returns nothing.I am trying to list all of the processes that no longer have their executables available on disk.
Will this work for you?
#!/bin/bash
for i in $(ls /proc | awk '/^[[:digit:]]+/{print $1}'); do
if [ -h /proc/$i/exe ]; then
echo -n "$i: "
if readlink /proc/$i/exe >/dev/null 2>&1 ; then
echo "executable exists"
else
echo "executable not found"
fi
fi
done
I've updated your script to make it work. Notice that -f checks whether a file name represents a regular file. I would return false for a symbolic link:
pid="0"
while [ $pid -lt 32769 ]
do
if [ -d /proc/$pid ]; then
if [ -h /proc/$pid/exe ]; then
echo $pid
readlink /proc/$pid/exe
fi
fi
pid=$[$pid+1]
done
you can read returned value after any command in shell by printing $? variable:
readlink
echo $?
if link is invalid, $? will be bigger than 0.
however if link exist and actual file is deleted, you can use something like:
ls `readlink somelink`
readlink -f `ls --dereference /proc/$pid/exe`
I want to run the command:
nc localhost 9998
Then I want my script to monitor a file and echo the contents of the file to this sub process whenever the file changes.
I can't work out the re-direction scheme. How can get access to the STDIN of the subprocess?
How about
tail -f $file |nc localhost 9998
Edit:
Since you already have a buffer, then you can try something like this:
while [ 1 ]; do
# Your stuff here.
buf=yourfunctionhere
buffer=$buffer$buf
if [ ! -z $buffer ]; then
echo $buffer |nc localhost 9998
# Empty buffer on success.
if [ $? -eq 0 ]; then
buffer="";
fi
fi
done
mkfifo X
some_program <X >output &
create_input >X
some_program will block reading X until create_input writes to it.
Two solutions that I found acceptable:
1) use coprocess, this way we have access to stdin and stdout of the process created by the coprocess command via the COPROC[0/1] array.
2) What I ultimately did is separate my application into two code blocks as shown below. The first block writes to stdout, that is then piped to the stdin of the second block. This gives me a clean way to buffer data when there are issues with netcat in the second code block:
{ while true;
write to STDOUT; } |
{ while true
nc localhost 9998 }
(in actuality the script is far more complex as the second command provides to-disk buffering when netcat is unable to connect, but the use of the pipe provides buffering so that data isn't lost when a network issue interrupts netcat)
I found a solution using diff and a simple bash script.
The following script execute cat $file > $namedpipe when file change. This is the script I made check-file.sh:
#!/bin/bash
file=$1
tmp=`mktemp`
cp "$file" "$tmp"
namedpipe=`mktemp`
rm -rf $namedpipe
mkfifo $namedpipe
function cleanup() {
echo "end of program"
rm -rf $tmp
rm -rf $namedpipe
exit 1;
}
trap cleanup SIGINT
tail -f $namedpipe 2> /dev/null | netcat localhost 9998 &
while true; do
diff=$(diff "$file" "$tmp")
if [ ! -z "$diff" ]; then
cat $file > $namedpipe
cp $file $tmp
fi
sleep 1
done
This script take as an input the name of a file. For example try these commands in your environment (whit netcat -l 9998 running):
touch /tmp/test
bash check-file.sh /tmp/test &
echo "change 1" > /tmp/test
sleep 1
echo "change 2" > /tmp/test
sleep 1
echo "change 3" > /tmp/test
Note: The temp file get cleaned up by the trap, so you can interrupt this script gracefuly.