I have tried all kinds of filters using grep to try and solve this but just cannot crack it.
cpumem="$(ps aux | grep -v 'grep' | grep 'firefox-bin' | awk '{printf $3 "\t" $4}'
I am extracting the CPU and Memory usage for a process and when I run it from the command line, I get the 2 fields outputted correctly:
ps aux | grep -v 'grep' | grep 'firefox-bin' | awk '{printf $3 "\t" $4}'
> 1.1 4.4
but the same command executed from within the bash script produces this:
cpumem="$(ps aux | grep -v 'grep' | grep 'firefox-bin' | awk '{printf $3 "\t" $4}')"
echo -e cpumem
> 1.1 4.40.0 0.10.0 0.0
I am guessing that it is picking up 3 records, but I just don't know where from.
I am filtering out any other grep processes by using grep -v 'grep', can someone offer any suggestions or a more reliable way ??
Maybe you have 3 records because 3 firefox are running (or one is running, and it is threading itself).
You can avoid the grep hazzle by giving ps and option to select the processes. E.g. the -C to select processes by name. With ps -C firefox-bin you get only the firefox processes. But this does not help at all, when there is more than one process.
(You can also use the ps option to output only the columns you want, so your line would be like
ps -C less --no-headers -o %cpu,%mem
).
For the triple-record you must come up with a solution, what should happen, where more than one is running. In a multiuser environment with programms that are threading there can always be situations where you have more than one process of a kind. There are many possible solution where none can help you, as you dont say, way you are going to do with it. One can think of solutions like selecting only from one user, and only the one with the lowest pid, or the process-leader in case of groups, to change the enclosing bash-script to use a loop to handle the multiple values or make it working somehow different when ps returns multiple results.
I was not able to reproduce the problem, but to help you debug, try print $11 in your awk command, that will tell you what process it is talking about
cpumem="$(ps aux | grep -v 'grep' | grep 'firefox-bin' | awk '{printf $3 "\t" $4 "\t" $11 "\n"}')"
echo -e cpumem
It's actually an easy fix for the output display; In your echo statement, wrap the variable in double-quotes:
echo -e "$cpumem"
Without using double-quotes, newlines are not preserved by converting them to single-spaces (or empty values). With quotes, the original text of the variable is preserved when outputted.
If your output contains multiple processes (i.e. - multiple lines), that means your grep actually matched multiple lines. There's a chance a child-process is running for firefox-bin, maybe a plugin/container? With ps aux, the 11th column will tell you what the actual process is, so you can update your awk to be the following (for debugging):
awk '{printf $3 "\t" $4 "\t" $11}'
Related
I have read that egrep is deprecated in favour of grep -E so I'm looking back at my code and changing it where I find it.
But I see that the results are not always as expected.
With egrep, I get my list of running Oracle instances:
ps -ef|grep [p]mon|awk -F'ora_pmon_' '{print $NF}'|egrep -v 'ASM|^$'
halana
bila
halsasa
loana
However with grep -E, I get part of the awk in the results:
ps -ef|grep [p]mon|awk -F'ora_pmon_' '{print $NF}'|grep -Ev 'ASM|^$'
halana
bila
halsasa
{print $NF}
loana
Excluding 'print' obviously works but is it the right way to go about it?:
ps -ef|grep [p]mon|awk -F'ora_pmon_' '{print $NF}'|grep -Ev 'ASM\|^$|print'
halana
bila
halsasa
loana
Is this effect due to the fact that grep -E allows additional regular expression syntax?
Suggesting to simplify your line, eliminate all grep commands:
pgrep -af 'pmon'|awk -F'ora_pmon_' '!/ASM|^$/{print $NF}'
Fold first grep command into pgrep command.
Fold second grep command into awk scirpt !/ASM|^$/{print $NF}
About grep -E vs egrep
There is no difference whatsoever between these commands (they're even provided by the same executable on most operating systems); your old code was vulnerable to this bug too, and if you didn't see it, that's just a matter of being "lucky" in ps getting enough of the process list read before the shell gets to setting up the awk part of the pipeline.
Solving Your Problem
The right answer is already given by #DudiBoy, but the answer with the smallest possible change would be to make your awk (assuming it has GNU extensions and accepts regexes in the field separator specification) escape the string pmon the same way your first grep command does:
ps -ef|grep '[p]mon'|awk -F'ora_[p]mon_' '{print $NF}'|grep -Ev 'ASM|^$'
I need to use awk to see what users are logged in the computer, create a file with their names and inside that file print the pid of the process they're running. I've used this, but it does not work:
who | awk '{for(i = 0; i < NR; i++)
system("ps -u " $1 "| tail +2 | awk '{print $1}' >" $1".log")
}'
Is there any way to do this?
Thanks a lot!
To achieve your goal of using awk to create those files, I would start with ps rather than with who. That way, ps does more of the work so that awk can do less. Here is an example that might work for you. (No guarantees, obviously!)
ps aux | awk 'NR>1 {system("echo " $2 " >> " $1 ".txt")}'
Discussion:
The command ps aux prints a table describing each active process, one line at a time. The first column of each line contains the name of the process's user, the second column its PID. The line also contains lots of other information, which you can play with as you improve your script. That's what you pipe into awk. (All this is true for Linux and the BSDs. In Cygwin, the format is different.)
Inside awk, the pattern NR>1 gets rid of the first line of the output, which contains the table headers. This line is useless for the files you want awk to generate.
For all other lines in the output of ps aux, awk adds the PID of the current process (ie, $2) to the file username.txt, using $1 for username. Because we append with >> rather than overwriting with >, all PIDs run by the user username end up being listed, one line at a time, in the file username.txt.
UPDATE (Alternative for when who is mandatory)
If using who is mandatory, as noted in a comment to the original post, I would use awk to strip needless lines and columns from the output of who and ps.
for user in $(who | awk 'NR>1 {print $1}')
do
ps -u "$user" | awk 'NR>1' > "$user".txt
done
For readers who wonder what the double-quotes around $user are about : Those serve to guard against globbing (if $user contains asterisks (*)) and word splitting (if $user contains whitespace).
I will leave my original answer stand for the benefit of any readers with more freedom to choose the tools for their job.
Is that what you had in mind?
Use Top command which repeats 5 times, pipe the results to Grep and Cut command to print the PID for init process on your screen.
Hi all, I have my line of code:
top -n 5 | grep "init" | cut -d" " -f3 > topdata
But I cannot see any output to verify that it's working.
Also, the next script asks me to use a one line command which shows the total memory used in megabytes. I'm supposed to pipe results from Free to Grep to select or filter the lines with the pattern "Total:" then pipe that result to Cut and display the number representing total memory used. So far:
free -m -t | grep "total:" | cut -c25-30
Also not getting any print return on that one. Any help appreciated.
expanding on my comments:
grep is case sensitive. free says "Total", you grep "total". So no match! Either grep for "Total" or use grep -i.
Instead of cut, I prefer awk when I need to get a number out of a line. You do not know what length the number will be, but you know it will be the first number after Total:. So:
free -m -t | grep "Total:" | awk '{print $2}'
For your top command, if you have no init process (which you should, but it would probably not show in top), just grep for something else to see if your code works. I used cinnamon (running Mint). The top command is:
top -n 5 | grep "cinnamon" | awk '{print $1}'
Replace "cinnamon" by "init" for your requirement. Why $1 in the awk? My top puts the PID in the first column. Adjust accordingly.
Overall, using cut is good when you have a string that is delimited by some character. Ex. aaa;bbb;ccc, you would cut on -d';'. But here the numbers might have different lengths so using cut is not (IMHO) the best solution.
The init process has PID 1, to there's no reason to do like this.
To find the PID of a process in general, I'd recommend:
pidof <name>
Here's my issue, i know how to count the files using the following two strategies but i have a problem with each one.
I am using '.sh' extension.
First:
count=`echo $2 | awk -F, {'print NF'}`
causes my program to throw an error at me: awk: cannot execute - No such file or directory
Secondly:
count=`echo $2 | tr -cd , | wc -c`
Works if you have multiple values separated by commas, however, it will not work if the input is a single item with no commas.
Like i said, this was previously working with the awk but for some reason when i ran it on the physical device instead of the virtual machine it gave me that error.
any ideas?
Thing I know are NOT the issue:
Version of shell is the same.
Try count=$(echo ${2} | awk -F, '{print NF}') instead - you have your braces and quotes inside-out.
Although, it seems your bigger problem is that awk appears to not be executable... You might try which awk and ls -l $(which awk) to see what's up with that...
I'm trying to create a shell script getting the process id of the Skype app on my Mac.
ps -clx | grep 'Skype' | awk '{print $2}' | head -1
The above is working fine, but there are two problems:
1)
The grep command would get all process if their name just contains "Skype". How can I ensure that it only get the result, if the process name is exactly Skype?
2)
I would like to make a shell script from this, which can be used from the terminal but the process name should be an argument of this script:
#!/bin/sh
ps -clx | grep '$1' | awk '{print $2}' | head -1
This isn't returning anything. I think this is because the $2 in the awk is treated as an argument too. How can I solve this?
Your ps -cl1 output looks like this:
UID PID PPID F CPU PRI NI SZ RSS WCHAN S ADDR TTY TIME CMD
501 185 172 104 0 31 0 2453272 1728 - S ffffff80145c5ec0 ?? 0:00.00 httpd
501 303 1 80004004 0 31 0 2456440 1656 - Ss ffffff8015131300 ?? 0:11.78 launchd
501 307 303 4004 0 33 0 2453456 7640 - S ffffff8015130a80 ?? 0:46.17 distnoted
501 323 303 40004004 0 33 0 2480640 9156 - S ffffff80145c4dc0 ?? 0:03.29 UserEventAgent
Thus, the last entry in each line is your command. That means you can use the full power of regular expressions to help you.
The $ in a regular expression means the end of the string, thus, you could use $ to specify that not only does the output must have Skype in it, it must end with Skype. This means if you have a command called Skype Controller, you won't pull it up:
ps -clx | grep 'Skype$' | awk '{print $2}' | head -1
You can also simplify things by using the ps -o format to just pull up the columns you want:
ps -eo pid,comm | grep 'Skype$' | awk '{print $1}' | head -1
And, you can eliminate head by simply using awk's ability to select your line for you. In awk, NR is your record number. Thus you could do this:
ps -eo pid,comm | grep 'Skype$' | awk 'NR == 1 {print $1}'
Heck, now that I think of it, we could eliminate the grep too:
ps -eo pid,comm | awk '/Skype$/ {print $1; exit}'
This is using awk's ability to use regular expressions. If the line contains the regular expression, 'Skype$', it will print the first column, then exit
The only problem is that if you had a command Foo Skype, this will also pick it up. To eliminate that, you'll have to do a bit more fancy footwork:
ps -eo pid,comm | while read pid command
do
if [[ "$command" = "Skype" ]]
then
echo $pid
break
fi
done
The while read is reading two variables. The trick is that read uses white space to divide the variables it reads in. However, since there are only two variables, the last one will contain the rest of the entire line. Thus if the command is Skype Controller, the entire command will be put into $command even though there's a space in it.
Now, we don't have to use a regular expression. We can compare the command with an equality.
This is longer to type in, but you're actually using fewer commands and less piping. Remember awk is looping through each line. All you're doing here is making it more explicit. In the end, this is actually much more efficient that what you originally had.
If pgrep is available on Mac, you can use pgrep '^Skype$'. This will list the process id of all processes called Skype.
You used the wrong quotes in your script:
ps -clx | grep "$1" | awk '{print $2}' | head -1
or
pgrep "^$1$"
The problem with your second example is that the $1 is in single quotes, which prevents bash from expanding the variable. There is already a utility that accomplishes what you want without manually parsing ps output.
pgrep "$1"
You can do this in AppleScript:
tell application "System Events"
set skypeProcess to the process "Skype"
set pid to the unix id of skypeProcess
pid
end tell
which means you can use 'osascript' to get the PID from within a shell script:
$ osascript -e "tell application \"System Events\"" -e "set skypeProcess to the process \"Skype\"" -e "set pid to the unix id of skypeProcess" -e "pid" -e "end tell"
3873
You can format the output of ps using the -o [field],... and list by process name using -C [command_name] ;however, ps will still print the column header, which can be removed by piping it through grep -v PID
ps -o pid -C "$1" |grep -v PID
where $1 would be the command name (in this case Skype)
I'd so something like:
ps aux | grep Skype | awk 'NR==1 {print $2}'
==== UPDATE ====
Use the parameter without quotes and use single quotes for awk
#!/bin/bash
ps aux | grep $1 | awk 'NR==1 {print $2}'
Method 1 - Use awk
I don't see any reason to use the -l flag (long format), I also don't see any reason to use grep and awk at the same time: awk has grep capability built in. Here is my plan: use ps and output just 2 columns: pid and command, then use awk to pick out what you want:
ps -cx -o pid,command | awk '$2 == "Skype" { print $1 }'
Method 2 - Use bash
This method has the advantage that if you already script in bash, you don't even need awk, which save one process. The solution is longer than the other method, but very straight forward.
#!/bin/bash
ps -cx -o pid,command | {
while read pid command
do
if [ "_$command" = "_$1" ]
then
# Do something with the pid
echo Found: pid=$pid, command=$command
break
fi
done
}
pgrep myAwesomeAppName
This works great under Catalina 10.15.2
Use double quotes to allow bash to perform variable substitution.
Single quotes disable bash variable substitution mechanism.
ps -clx | grep "$1" | awk "{print $2}" | head -1