Assuming a shell script(commands.sh) with few commands.
I need to write a script which sends the output of commands executed by commands.sh to a file f1.csv
if file size exceeds 1MB then the output flowing should go to file f2.csv
if the file size exceeds 1 mb again here,the output flowing should go to file f3.csv
if f3.csv exceeds the size 1mb,then the older f1 should be deleted and again new file f1 should be created,
output flowing should be to written to f1. This process should go on .
I can write the crontab file, just the shell script is a bit tricky
I have been experimenting:
#!/usr/bin/env bash
PREFIX="f"
# Maximum size after which you want a new file in bytes
MAX_SIZE=1048576
LAST_FILE=`ls "$prefix"*.csv | tail -1`
# Check if file exists and if it does not, create it.
if [[ -z "$LAST_FILE" ]]
then
LAST_FILE=$PREFIX"1.csv"
touch $LAST_FILE
fi
LAST_FILE_NO=`echo $LAST_FILE | sed s/$PREFIX/''/ | sed s/.csv/''/`
LAST_FILE_SIZE=`stat -c %s $LAST_FILE`
if [ `stat -c %s $LAST_FILE` -lt 200 ]
then
`/bin/sh ./sam.sh >> $LAST_FILE`
else
UPCOMING_FILE_NO=$((LAST_FILE_NO+1))
`/bin/sh ./sam.sh >> $PREFIX$UPCOMING_FILE_NO.csv`
fi
help is appreciated guys.
EDIT: Have got the secondary shell script to work too...
Now if anyone could help me with resetting after 3 files are done and starting from f1.
thanks
It sounds like you'd be better off using logrotate, depending on how your script is running. If you are running 'commands.sh' on a cron, you can have logrotate rotate out the logs. There is a good guide on logrotate here:
http://linuxers.org/howto/howto-use-logrotate-manage-log-files
If your commands.sh isn't going to be on a cron, meaning it's not a regular time interval that triggers it, you could manually set up a log rotation at the beginning of your script. I once had to do something similar. I found this guide really useful:
http://wazem.blogspot.com/2013/11/simple-bash-log-rotate-function.html
Related
Can someone fix this for me.
It should copy a version log file to backup after moving to a repo directory
Then it automatically appends line given as input to the log file with some formatting.
That's it.
Assume existence of log file and test directory.
#!/bin/bash
cd ~/Git/test
cp versionlog.MD .versionlog.MD.old
LOGDATE="$(date --utc +%m-%d-%Y)"
read -p "MSG > " VHMSG |
VHENTRY="- **${LOGDATE}** | ${VHMSG}"
cat ${VHENTRY} >> versionlog.MD
shell output
virufac#box:~/Git/test$ ~/.logvh.sh
MSG > testing script
EOF
EOL]
EOL
e
E
CTRL + C to get out of stuck in reading lines of input
virufac#box:~/Git/test$ cat versionlog.MD
directly outputs the markdown
# Version Log
## version 0.0.1 established 01-22-2020
*Working Towards Working Mission 1 Demo in 0.1 *
- **01-22-2020** | discovered faker.Faker and deprecated old namelessgen
EOF
EOL]
EOL
e
E
I finally got it to save the damned input lines to the file instead of just echoing the command I wanted to enter on the screen and not executing it. But... why isn't it adding the lines built from the VHENTRY variable... and why doesn't it stop reading after one line sometimes and this time not. You could see I was trying to do something to tell it to stop reading the input.
After some realizing a thing I had done in the script was by accident... I tried to fix it and saw that the | at the end of the read command was seemingly the only reason the script did any of what it did save to the file in the first place.
I would have done this in python3 if I had know this script wouldn't be the simplest thing I had ever done. Now I just have to know how you do it after all the time spent on it so that I can remember never to think a shell script will save time again.
Use printf to write a string to a file. cat tries to read from a file named in the argument list. And when the argument is - it means to read from standard input until EOF. So your script is hanging because it's waiting for you to type all the input.
Don't put quotes around the path when it starts with ~, as the quotes make it a literal instead of expanding to the home directory.
Get rid of | at the end of the read line. read doesn't write anything to stdout, so there's nothing to pipe to the following command.
There isn't really any need for the VHENTRY variable, you can do that formatting in the printf argument.
#!/bin/bash
cd ~/Git/test
cp versionlog.MD .versionlog.MD.old
LOGDATE="$(date --utc +%m-%d-%Y)"
read -p "MSG > " VHMSG
printf -- '- **%s** | %s\n' "${LOGDATE}" "$VHMSG" >> versionlog.MD
I need to run script to parse the value from csv every five minutes but should not parse the all the values all the time it should be from the last point.
Really just putting some flesh on #hek2mgl's suggestion and implementing it for you.
I store the last known length of the logfile in another file called lastlength.
#!/bin/bash
LOGFILE=somelog.csv
LASTLEN=lastlength
# Pre-set seek to start of file...
seek=0
# ... but overwrite if there was a previously seen value
[ -f lastlength ] && seek=$(cat lastlength)
echo DEBUG: Starting from offset $seek
# Update last seen length into file - parameters to "stat" will differ on Linux
stat -f "%Dz" "$LOGFILE" > "$LASTLEN"
# Get last line of file starting from previous position
dd if="$LOGFILE" bs=$seek skip=1 2> /dev/null | tail -1
I am using OSX, so if you are using Linux, the parameters to the stat command in the second to last line will be different, probably
stat -c%s "$LOGFILE" > "$LASTLEN"
I'll leave you to put it into your crontab so it gets called every 5 minutes.
for my first bash project I am developing a simple bash script that shows basic information about my system:
#!/bash/sh
UPTIME=$(w)
MHZ=$(cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq)
TEMP=$(cat /sys/class/thermal/thermal_zone0/temp)
#UPTIME shows the uptime of the device
#MHZ shows the overclocked specs
#TEMP shows the current CPU Temperature
echo "$UPTIME" #displays uptime
echo "$MHZ" #displays overclocked specs
echo "$TEMP" #displays CPU Temperature
MY QUESTION: How can I code this so that the uptime and CPU temperature refresh every 2seconds without re-generating the code new every time (I just want these two variables to update without having to enter the file path again and re-running the whole script).
This code is already working fine on my system but after it executes in the command line, the information isn't updating because it executed the command and is standing by for the next command instead of updating the variables such as UPTIME in real time.
I hope someone understands what I am trying to achieve, sorry about my bad wordings of this idea.
Thank you in advance...
I think it will help you. You can use the watch command for updating that for every two seconds without the loop.
watch ./filename.sh
It will give you the update of that command for every two second.
watch - execute a program periodically, showing output fullscreen
Not sure to really understand the main goal, but here's an answer to the basic question "How can I code this so that the uptime and CPU temperature refresh every two seconds ?" :
#!/bash/sh
while :; do
UPTIME=$(w)
MHZ=$(cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq)
TEMP=$(cat /sys/class/thermal/thermal_zone0/temp)
#UPTIME shows the uptime of the device
#MHZ shows the overclocked specs
#TEMP shows the current CPU Temperature
echo "$UPTIME" #displays uptime
echo "$MHZ" #displays overclocked specs
echo "$TEMP" #displays CPU Temperature
sleep 2
done
I may suggest some modifications.
For such simple job I may recommend no to use external utilities. So instead of $(cat file) you could use $(<file). This is a cheaper method as bash does not have to launch cat.
On the other hand if reading those devices returns only one line, you can use the bash built-in read like: read ENV_VAR <single_line_file. It is even cheaper. If there are more lines and for example you want to read the 2nd line, you could use sg like this: { read line_1; read line2;} <file.
As I see w provides much more information and as I assume you need only the header line. This is exactly what uptime prints. The external utility uptime reads the /proc/uptime pseudo file. So to avoid to call externals, you can read this pseudo file directly.
The looping part also uses the external sleep(1) utility. For this the timeout feature of the read internal could be used.
So in short the script would look like this:
while :; do
# /proc/uptime has two fields, uptime and idle time
read UPTIME IDLE </proc/uptime
# Not having these pseudo files on my system, the whole line is read
# Maybe some formatting is needed. For MHZ /proc/cpuinfo may be used
read MHZ </sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
read TEMP </sys/class/thermal/thermal_zone0/temp
# Bash supports only integer arithmetic, so chomp off float
UPTIME_SEC=${UPTIME%.*}
UPTIME_HOURS=$((UPTIME_SEC/3600))
echo "Uptime: $UPTIME_HOURS hours"
echo $MHZ
echo $TEMP
# It reads stdin, so pressing an ENTER it returns immediately
read -t 2
done
This does not call any external utility and does not make any fork. So instead of executing 3 external utilities (using the expensive fork and execve system calls) in every 2 seconds this executes none. Much less system resources are used.
you could use while [ : ] and sleep 2
You need the awesome power of loops! Something like this should be a good starting point:
while true ; do
echo 'Uptime:'
w 2>&1 | sed 's/^/ /'
echo 'Clocking:'
sed 's/^/ /' /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
echo 'Temperature:'
sed 's/^/ /' /sys/class/thermal/thermal_zone0/temp
echo '=========='
sleep 2
done
That should give you your three sections, with the data of each nicely indented.
I'm trying to redirect(?) my standard error/output to a text file.
I did my research, but for some reason the online answers are not working for me.
What am I doing wrong?
cd /home/user1/lists/
for dir in $(ls)
do
(
echo | $dir > /root/user1/$dir" "log.txt
) > /root/Desktop/Logs/Update.log
done
I also tried
2> /root/Desktop/Logs/Update.log
1> /root/Desktop/Logs/Update.log
&> /root/Desktop/Logs/Update.log
None of these work for me :(
Help please!
Try this for the basics:
echo hello >> log.txt 2>&1
Could be read as: echo the word hello, redirecting and appending STDOUT to the file log.txt. STDERR (file descriptor 2) is redirected to wherever STDOUT is being pointed. Note that STDOUT is the default and thus there is no "1" in front of the ">>". Works on the current line only.
To redirect and append all output and error of all commands in a script, put this line near the top. It will be in effect for the length of the script instead of doing it on each line:
exec >>log.txt 2>&1
If you are trying to obtain a list of the files in /home/user1/lists, you do not need a loop at all:
ls /home/usr1/lists/ >Update.log
If you are attempting to run every file in the directory as an executable with a newline as its input, and collect the output from all these programs in Update.log, try this:
for file in /home/user1/lists/*; do
echo | "$file"
done >Update.log
(Notice how we avoid the useless use of ls and how there is no redirection inside the loop.)
If you want to create an empty file called *.log.txt for each file in the directory, you would do
for file in /home/user1/lists/*; do
touch "$(basename "$file")"log.txt
done
(Using basename to obtain the file name without the directory part avoids the cd but you could do it the other way around. Generally, we tend to avoid changing the directory in scripts, so that the tool can be run from anywhere and generate output in the current directory.)
If you want to create a file containing a single newline, regardless of whether it already exists or not,
for file in /home/user1/lists/*; do
echo >"$(basename "$file")"log.txt
done
In your original program, you redirect the echo inside the loop, which means that the redirection after done will not receive any output at all, so the created file will be empty.
These are somewhat wild guesses at what you might actually be trying to accomplish, but should hopefully help nudge you slightly in the right direction. (This should properly be a comment, I suppose, but it's way too long and complex.)
I wrote a script that gets load and mem information for a list of servers by ssh'ing to each server. However, since there are around 20 servers, it's not very efficient to wait for the script to end. That's why I thought it might be interesting to make a crontab that writes the output of the script to a file, so all I need to do is cat this file whenever I need to know load and mem information for the 20 servers. However, when I cat this file during the execution of the crontab it will give me incomplete information. That's because the output of my script is written line by line to the file instead of all at once at termination. I wonder what needs to be done to make this work...
My crontab:
* * * * * (date;~/bin/RUP_ssh) &> ~/bin/RUP.out
My bash script (RUP_ssh):
for comp in `cat ~/bin/servers`; do
ssh $comp ~/bin/ca
done
Thanks,
niefpaarschoenen
You can buffer the output to a temporary file and then output all at once like this:
outputbuffer=`mktemp` # Create a new temporary file, usually in /tmp/
trap "rm '$outputbuffer'" EXIT # Remove the temporary file if we exit early.
for comp in `cat ~/bin/servers`; do
ssh $comp ~/bin/ca >> "$outputbuffer" # gather info to buffer file
done
cat "$outputbuffer" # print buffer to stdout
# rm "$outputbuffer" # delete temporary file, not necessary when using trap
Assuming there is a string to identify which host the mem/load data has come from you can update your txt file as each result comes in. Asuming the data block is one line long you could use
for comp in `cat ~/bin/servers`; do
output=$( ssh $comp ~/bin/ca )
# remove old mem/load data for $comp from RUP.out
sed -i '/'"$comp"'/d' RUP.out # this assumes that the string "$comp" is
# integrated into the output from ca, and
# not elsewhere
echo "$output" >> RUP.out
done
This can be adapted depending on the output of ca. There is lots of help on sed across the net.