I'm setting up a logging script with Ruby and am having some difficulties with getting the load averages as a variable. I'm using:
uptime | awk '{print $10}'
to get the current 1 minute time stamp, but I'm having trouble getting it without a trailing comma. I could edit the string later, but that seems less efficient. Is there an edit that will simply remove the , from the return?
How about:
cut -f 1 -d " " /proc/loadavg
The uptime command reads /proc/loadavg and then adds the commas.
In the end, it also works through /proc/loadavg, but the usage is a little more idiomatic, so I thought I'd mention the sys-cpu Gem (which existed even in 2013 :)) as well:
gem install sys-cpu
require 'sys-cpu'
puts Sys::CPU.load_avg
... which will give you a nice array: [0.72, 1.14, 1.11].
Related
I noticed that RHEL 8 and Fedora 30 don't update the utmp file properly.
As a result, commands such as 'who am i', 'last', 'w' etc print incorrect results (who am i actually doesn't print anything)
After a bit of googling, I found 'logname' which worked in this case but I read that gnome is dropping support for utmp altogether so it's a matter of time until this stops working too.
I wrote the following script which finds the login name of the user (even if he is using sudo the moment he runs the command) but it's way too complicated so I'm looking for alternatives.
LOGIN_UID=$(cat /proc/self/loginuid)
LOGIN_NAME=$(awk -v val=LOGIN_UID -F ":" '$3==val{print $1}' /etc/passwd)
Is there a simple alternative which is not based on proper updating of /var/run/utmp ?
Edit 1: Solutions that don't work $HOME, $USER and id return incorrect values when used in a script that has been run with the sudo command. who am i and logname depend on utmp which isn't always updated by the terminal.
Working solution: After a bit of searching, a simpler way than the aforementioned was found in https://unix.stackexchange.com/users/5685/frederik-deweerdt 's comment to his own answer
Link to answer which contains the commment: https://unix.stackexchange.com/a/74312
Answer 1
stat -c "%U" $(tty)
Second answer found at https://stackoverflow.com/a/51765389/10630167
Answer 2
`pstree -lu -s $$ | grep --max-count=1 -o '([^)]*)' | head -n 1 | sed 's/[()]//g'`
Your question is not well-defined because if X and Y are not working, what are the chances that Z will work? This depends entirely on the precise failure mode you are attempting to handle, and there is nothing in your question to reveal the specific circumstances in which you need this.
With that out of the way, perhaps look at the POSIX id command, which has explicit options to print the real (login) or effective (after any setuid command) user id with -r or -u, respectively. Of course, the precise means by which it obtains this information are not specified, and will remain implementation-dependent, and thus might or might not work on your platform under your specific circumstances.
As an aside, here is a refactoring of your code to avoid polluting the variable name space with two separate variables.
LOGIN_NAME=$(awk 'NR==FNR { val=$0; next }
$3==val{print $1}' /proc/self/loginuid FS=":" /etc/passwd)
My file contains something like the below:
X-TM-AS-Product-Ver: IMSVA-8.2.0.1391-8.0.0.1202-22662.005
X-TM-AS-Result: No--0.364-7.0-31-10
X-imss-scan-details: No--0.364-7.0-31-10
X-TMASE-Version: IMSVA-8.2.0.1391-8.0.1202-22662.005
X-TMASE-Result: 10--0.363600-5.000000
X-TMASE-MatchedRID: 40jyuBT4FtykMGOaBzW2QbxygpRxo469FspPdEyOR1qJNv6smPBGj5g3
9Rgsjteo4vM1YF6AJbZcLc3sLtjOty5V0GTrwsKpl6V6bOpOzUAdzA5USlz33EYWGTXfmDJJ3Qf
wsVk0UbuGrPnef/I+eo9h73qb6JgVCR2fClyPE+EPh2lMKov3fdtvzshqXylpWZGeMhmJ7ScqBW
z6M5VHW/fngY5M/1HkzhvqqZL61o+ZdBoyruxjzQ==
This is my real text! I need to extract this line!
The existing code, written in the past by someone else, executes the below line:
cat $my_file | egrep -v "^(X-TM-AS)"
| egrep -v "X-imss-scan-details"
supposedly to remove all those key value lines which start with "X-".
The above piece of code has been working fine up until today because keys starting with X-TMASE has never been among the keys in the past. It has started to appear in the files today, and therefore it has caused the code to fail in extraction of the useful data.
Among the newly added keys, it seems to me that X-TMASE-MatchedRID is the one creating the headache for us, as it has a value which spans multiple lines:
X-TMASE-MatchedRID: 40jyuBT4FtykMGOaBzW2QbxygpRxo469FspPdEyOR1qJNv6smPBGj5g3
9Rgsjteo4vM1YF6AJbZcLc3sLtjOty5V0GTrwsKpl6V6bOpOzUAdzA5USlz33EYWGTXfmDJJ3Qf
wsVk0UbuGrPnef/I+eo9h73qb6JgVCR2fClyPE+EPh2lMKov3fdtvzshqXylpWZGeMhmJ7ScqBW
z6M5VHW/fngY5M/1HkzhvqqZL61o+ZdBoyruxjzQ==
Initially I tried the below:
cat $my_file | egrep -v "^(X-TM-AS)"
| egrep -v "X-imss-scan-details"
| egrep -v "^(X-TMASE-)"
But it didn't work. It didn't completely eliminate the value for X-TMASE-MatchedRID:
9Rgsjteo4vM1YF6AJbZcLc3sLtjOty5V0GTrwsKpl6V6bOpOzUAdzA5USlz33EYWGTXfmDJJ3Qf
wsVk0UbuGrPnef/I+eo9h73qb6JgVCR2fClyPE+EPh2lMKov3fdtvzshqXylpWZGeMhmJ7ScqBW
z6M5VHW/fngY5M/1HkzhvqqZL61o+ZdBoyruxjzQ==
This is my real text! I need to extract this line!
I wanted the output to be:
This is my real text! I need to extract this line!
That is, I don't want any metadata to be seen in the output.
Any idea how that can be achieved using egrep or any equivalent command?
If you just want to remove the first paragraph some other command is better, for example sed
sed '1,/^$/ d' "$my_file"
Please advise on replacing a variable with latest date & time.
Here is my requirement.
FN='basename$0'
TS=`date '+%m/%d/%Y %T'`
QD='08/27/2014 16:25:45'
Then I have a query to run. After it has run, I need to take $TS (current system date & time) and assign it as a value to the $QD variable. This is a loop process and gets updated every time the script runs.
I've tried using sed but was not successful.
Please help.
Programatically modifying your script to have a different timestamp constant is absolutely and emphatically the wrong way to handle this problem.
Instead, when you want to mark that the query has been done, simply touch a file:
touch lastQueryCompletion
...and when you want to know when the query was last done, check that file's timestamp:
# with GNU date
QD=$(date -r lastQueryCompletion '+%m/%d/%Y %T')
# or, with Mac OS X stat
QD=$(stat -t '%Y/%m/%d %H:%M:%S' -f '%Sm' lastQueryCompletion)
Although you haven't mentioned the overall goal that you wish to accomplish, I have a feeling something like this would be more robust than using sed to update an existing script file.
FN='basename$0'
TS=date '+%m/%d/%Y %T'
# Load the latest QD (from the last run)
[ -e ~/.QD.saved ] && QD="`cat ~/.QD.saved`"
QD='08/27/2014 16:25:45'
...Later in that file...
#Save the new QD variable
echo '$(date +$FORMAT)'" > ~/.QD.saved
Although I'm not sure if sed is the tool you're looking, I believe that your command would have to go like this:
sed -i -r 's/^QD=.*/QD="$TS"/g' "$FN"
I'm assuming you're using gnu-sed, which with -i option tells to do an in-place substitution, rather then copying the input line to the pattern space.
Well, hope it helps.
Have a relatively simple question here. I need to run a function in the background in bash. Normally I would do it just like so:
FUNCTION &
but things are a bit more complicated than that. I have the following line that runs the main function for each record in a text database. I cant really edit this code all that much without vastly changing the rest of the entire project, but im still open to new ideas.
cat databases/$WAN | grep -v \# | while read LINE; do MAIN; done
I want to spawn a new terminal in background for each record to do a sort of parallel type processing, making things go much faster. Main takes a minute to process for each record. This however does not work.
cat databases/$WAN | grep -v \# | while read LINE; do MAIN &; done
Any suggestions?
* UPDATE *
Thanks for all the responses. Let me see if I can answer some of those questions.
gniourf_gniourf - Yes I know using cat like this is wrong. This was early on, and critical code, so I have not updated it yet. I now read into the while loop for most things I do. I will fix it eventually. You may be right about syntax. When I break it up like so, things seem to work now:
cat databases/$WAN | grep -v \# | while read LINE
do
MAIN & > /dev/null 2>&1
done
So that fixes the background problem. I wonder what was messed up in my single line syntax. Thanks
chepner - I don't believe LINE is a variable. I could be wrong though. Some things about Bash still confuse me. Maybe it is and is a variable that the entire record from the database gets stored to prior to processing.
Bruce K - Waiting is exactly what I was trying to avoid. If I let it run in the same terminal one at a time, it will slowly process each record in order. If I push each record to a seperate terminal for processing, all records will be processed simultaneously (at least in our eyes). The additional overhead is intentional in order to speed up how quickly the loop through the database occurs.
Radix - Yes you're right. I'll read up on that. Thanks for the link.
This worked for me:
$ function testt(){ echo "lineee is <$lineee>";}
$ grep 5432 /etc/services|while read lineee;do testt&done
lineee is <postgres 5432/udp # POSTGRES>
lineee is <postgres 5432/tcp # POSTGRES>
If, for some reason, your MAIN function is not seeing a LINE variable, you can try:
"export" the LINE variable beforehand:
$ export LINE
$ # do your thing
Or, pass the line read as an argument to the function:
$ function testt(){ LINE="$1"; echo "LINE is <$LINE>";}
$ grep 5432 /etc/services|while read LINE;do testt "$LINE"&done
Right now I am running a few programs with bash scripts (with Cygwin).
Basically what I am doing is after the program is starting, a loop is ran that checks that the program is still running.
I was doing:
while true
do
if [ "$(ps -W | grep -w name | gawk '{print $8,$9}' | gawk -F \\ '{print $4}')" == 'program' ];then
sleep 1
else
"start program" (whatever is needed here)
fi
done
But I started to realize having such a script multiple times is just causing unnecessary system resources to be used.
I tried doing an if then, elif, but it never goes past the first if.
I need it to go "alright the first if is negative, try the next, go to the end, start over".
Here is the copy of my script and I forgot to say I was using Cygwin but that really doesn't change anything cause it seems to still use normal bash scripting just maybe different paths to start files. http://pastebin.com/s8ZdPQMn and yes the h. is not there I just can't seem to edit the pastebin.
My overall plan is check that first SRPro is running, check the next, etc, only triggering if it's detected one is not running.
EDIT: I solved it. Not exactly sure why but in my original single file per program, gawk printing $4 at the end gave me what I wanted, but for some reason when doing it this way, it turned to $5. So changing $4 to $5 made the script work.
EDIT: One really strange issue though is, it will work minutes on end, then all the sudden get confused at times, and start 7 copies of one program or something. Also it can be random on which it starts.
You might find the wait command (try help wait from a bash prompt) useful. It's unclear exactly what you want, but as an example, here's a basic respawn function:
$ respawn () {
> while true
> do
> "${#}" &
> wait ${!}
> echo "respawning ..."
> done
> }
$ respawn some_program arg1 arg2 etc