i got a question about bash and awk, so, i'm going to filter the processes list from ps aux then i did filtering by grep, then i filter it again using awk to display only the pid and the path of the process, then save it to the corresponding ${pid} and ${path} field. the question is, when i done filtering the results using awk, i'm going to save those results on ${pid} for pid numbers and ${path} for process's path, but i got no idea at all on doing that thing. if anyone here have a solution it would be very appreciated.
Thanks
EDIT: here is the code
ps aux | grep 'firefox' | awk '{print $2 " " $11}'
then i don't know what to do to save the $2 content to ${pid} and $11 to ${path} and save those fields to the txt file again...
This should do it:
read pid path <<< $(ps aux | grep 'firefox' | awk '{print $2 " " $11}')
If all else fail remember that you have the disk that you can use. Pipe the result to a file and then process the file using awk or cut two times to assign the fields to the corresponding variables.
For example:
$result > tmp
pid=`cat tmp | cut -f 1`
path=`cat tmp | cut -f 2`
rm tmp
use set :
out=$(ps aux | grep 'nginx' | awk '{print $2 " " $11}' )
set $out
pid=$1
path=$2
echo $pid
echo $path
awk_output=($(ps aux | awk '/firefox/{print $2, $11}'))
pid="${awk_output[0]}"
path="${awk_output[1]}"
If your paths can contain spaces you'll need a different solution involving setting IFS.
Related
I have a problem with mktemp and grep.
OUT=$(mktemp /tmp/output.XXXXXXXXXX) || { echo "Failed to create temp file"; exit 1; }
awk -F: '{print $7}' /etc/passwd >> $OUT
grep -c $1 $OUT
In grep line, code not exits, not prints value of grep
Please, help me to solve that problem.
BlackPearl above probably is correct - $1 likely is empty during your program execution. As a result, the grep command looks like this: grep -c $OUT which tells grep to look for $OUT in the stdin. stdin is the keyboard (I suspect) so grep will wait forever (well, until you press Ctrl-D or Ctrl-C).
To solve your problem, specify a parameter when you execute your script.
You can also avoid the problem entirely by counting all of the unique values in your passwd file like this:
OUT=$(mktemp /tmp/output.XXXXXXXXXX) || { echo "Failed to create temp file"; exit 1; }
awk -F: '{print $7}' /etc/passwd >> "$OUT"
sort "$OUT" | uniq -c # count each unique value in passwd file column 7
I have the following script:
#!/bin/bash
TotalMem=$(top -n 1 | grep Mem | awk 'NR==1{print $4}') #integer
UsadoMem=$(top -n 1 | grep Mem | awk 'NR==1{print $8}') #integer
PorcUsado='scale=2;UsadoMem/TotalMem'|bc -l
echo $PorcUsado
The variable PorcUsado returns empty. I search for the use of bc, but something is wrong...
You're assigning PorcUsado to scale=2;UsadoMem/TotalMem and then piping the output of that assignment (nothing) into bc. You probably want the pipe inside a command substitution, e.g. (using a here string instead of a pipe):
PorcUsado=$(bc -l <<<'scale=2;UsadoMem/TotalMem')
But you'll also need to evaluate those shell variables - bc can't do it for you:
PorcUsado=$(bc -l <<<"scale=2;$UsadoMem/$TotalMem")
Notice the use of " instead of ' and the $ prefix to allow Bash to evaluate the variables.
Also, if this is the whole script, you can just skip the PorcUsado variable at all and let bc write directly to stdout.
#!/bin/bash
TotalMem=$(top -n 1 | grep Mem | awk 'NR==1{print $4}') #integer
UsadoMem=$(top -n 1 | grep Mem | awk 'NR==1{print $8}') #integer
bc -l <<<"scale=2;$UsadoMem/$TotalMem"
Why pipe top output at all? Seems too costly.
$ read used buffers < <(
awk -F':? +' '
{a[$1]=$2}
END {printf "%d %d", a["MemTotal"]-a["MemFree"], a["Buffers"]}
' /proc/meminfo
)
Of course, it can easily be a one-liner if you value brevity over readability.
I think the pipe is the problem try something like this:
PorcUsado=$(echo "scale=2;$UsadoMem/$TotalMem" | bc -l)
i haven't tested it yet but you have to echo the string and pipe the result from echo to bc.
EDIT: Correcting the variable names
You don't need grep or bc, since awk can search and do math all by itself:
top -n 1 -l 1 | awk '/Mem/ {printf "%0.2f\n",$8/$4;exit}'
I want to print the longest and shortest username found in /etc/passwd. If I run the code below it works fine for the shortest (head -1), but doesn't run for (sort -n |tail -1 | awk '{print $2}). Can anyone help me figure out what's wrong?
#!/bin/bash
grep -Eo '^([^:]+)' /etc/passwd |
while read NAME
do
echo ${#NAME} ${NAME}
done |
sort -n |head -1 | awk '{print $2}'
sort -n |tail -1 | awk '{print $2}'
Here the issue is:
Piping finishes with the first sort -n |head -1 | awk '{print $2}' command. So, input to first command is provided through piping and output is obtained.
For the second command, no input is given. So, it waits for the input from STDIN which is the keyboard and you can feed the input through keyboard and press ctrl+D to obtain output.
Please run the code like below to get desired output:
#!/bin/bash
grep -Eo '^([^:]+)' /etc/passwd |
while read NAME
do
echo ${#NAME} ${NAME}
done |
sort -n |head -1 | awk '{print $2}'
grep -Eo '^([^:]+)' /etc/passwd |
while read NAME
do
echo ${#NAME} ${NAME}
done |
sort -n |tail -1 | awk '{print $2}
'
All you need is:
$ awk -F: '
NR==1 { min=max=$1 }
length($1) > length(max) { max=$1 }
length($1) < length(min) { min=$1 }
END { print min ORS max }
' /etc/passwd
No explicit loops or pipelines or multiple commands required.
The problem is that you only have two pipelines, when you really need one. So you have grep | while read do ... done | sort | head | awk and sort | tail | awk: the first sort has an input (i.e., the while loop) - the second sort doesn't. So the script is hanging because your second sort doesn't have an input: or rather it does, but it's STDIN.
There's various ways to resolve:
save the output of the while loop to a temporary file and use that as an input to both sort commands
repeat your while loop
use awk to do both the head and tail
The first two involve iterating over the password file twice, which may be okay - depends what you're ultimately trying to do. But using a small awk script, this can give you both the first and last line by way of the BEGIN and END blocks.
While you already have good answers, you can also use POSIX shell to accomplish your goal without any pipe at all using the parameter expansion and string length provided by the shell itself (see: POSIX shell specifiction). For example you could do the following:
#!/bin/sh
sl=32;ll=0;sn=;ln=; ## short len, long len, short name, long name
while read -r line; do ## read each line
u=${line%%:*} ## get user
len=${#u} ## get length
[ "$len" -lt "$sl" ] && { sl="$len"; sn="$u"; } ## if shorter, save len, name
[ "$len" -gt "$ll" ] && { ll="$len"; ln="$u"; } ## if longer, save len, name
done </etc/passwd
printf "shortest (%2d): %s\nlongest (%2d): %s\n" $sl "$sn" $ll "$ln"
Example Use/Output
$ sh cketcpw.sh
shortest ( 2): at
longest (17): systemd-bus-proxy
Using either pipe/head/tail/awk or the shell itself is fine. It's good to have alternatives.
(note: if you have multiple users of the same length, this just picks the first, you can use a temp file if you want to save all names and use -le and -ge for the comparison.)
If you want both the head and the tail from the same input, you may want something like sed -e 1b -e '$!d' after you sort the data to get the top and bottom lines using sed.
So your script would be:
#!/bin/bash
grep -Eo '^([^:]+)' /etc/passwd |
while read NAME
do
echo ${#NAME} ${NAME}
done |
sort -n | sed -e 1b -e '$!d'
Alternatively, a shorter way:
cut -d":" -f1 /etc/passwd | awk '{ print length, $0 }' | sort -n | cut -d" " -f2- | sed -e 1b -e '$!d'
I have a line in a bash script that calculates the sum of unique IP requests to a certain page.
grep $YESTERDAY $ACCESSLOG | grep "$1" | awk -F" - " '{print $1}' | sort | uniq -c | awk '{sum += 1; print } END { print " ", sum, "total"}'
I am trying to get the value of sum to a variable outside the awk statement so I can compare pages to each other. So far I have tried various combinations of something like this:
unique_sum=0
grep $YESTERDAY $ACCESSLOG | grep "$1" | awk -F" - " '{print $1}' | sort | uniq -c | awk '{sum += 1; print ; $unique_sum=sum} END { print " ", sum, "total"}'
echo "${unique_sum}"
This results in an echo of "0". I've tried placing __$unique_sum=sum__ in the END, various combinations of initializing the variable (awk -v unique_sum=0 ...) and placing the variable assignment outside of the quoted sections.
So far, my Google-fu is failing horribly as most people just send the whole of the output to a variable. In this example, many lines are printed (one for each IP) in addition to the total. Failing a way to capture the 'sum' variable, is there a way to capture that last line of output?
This is probably one of the most sophisticated things I've tried in awk so my confidence that I've done anything useful is pretty low. Any help will be greatly appreciated!
You can't assign a shell variable inside an awk program. In general, no child process can alter the environment of its parent. You have to have the awk program print out the calculated value, and then shell can grab that value and assign it to a variable:
output=$( grep $YESTERDAY $ACCESSLOG | grep "$1" | awk -F" - " '{print $1}' | sort | uniq -c | awk '{sum += 1; print } END {print sum}' )
unique_sum=$( sed -n '$p' <<< "$output" ) # grab the last line of the output
sed '$d' <<< "$output" # print the output except for the last line
echo " $unique_sum total"
That pipeline can be simplified quite a lot: awk can do what grep can do, so first
grep $YESTERDAY $ACCESSLOG | grep "$1" | awk -F" - " '{print $1}'
is (longer, but only one process)
awk -F" - " -v date="$YESTERDAY" -v patt="$1" '$0 ~ date && $0 ~ patt {print $1}' "$ACCESSLOG"
And the last awk program just counts how many lines and can be replaced with wc -l
All together:
unique_output=$(
awk -F" - " -v date="$YESTERDAY" -v patt="$1" '
$0 ~ date && $0 ~ patt {print $1}
' "$ACCESSLOG" | sort | uniq -c
)
echo "$unique_output"
unique_sum=$( wc -l <<< "$unique_output" )
echo " $unique_sum total"
I have a text files with a line like this in them:
MC exp. sig-250-0 events & $0.98 \pm 0.15$ & $3.57 \pm 0.23$ \\
sig-250-0 is something that can change from file to file (but I always know what it is for each file). There are lines before and above this, but the string "MC exp. sig-250-0 events" is unique in the file.
For a particular file, is there a good way to extract the second number 3.57 in the above example using bash?
use awk for this:
awk '/MC exp. sig-250-0/ {print $10}' your.txt
Note that this will print: $3.57 - with the leading $, if you don't like this, pipe the output to tr:
awk '/MC exp. sig-250-0/ {print $10}' your.txt | tr -d '$'
In comments you wrote that you need to call it in a script like this:
while read p ; do
echo $p,awk '/MC exp. sig-$p/ {print $10}' filename | tr -d '$'
done < grid.txt
Note that you need a sub shell $() for the awk pipe. Like this:
echo "$p",$(awk '/MC exp. sig-$p/ {print $10}' filename | tr -d '$')
If you want to pass a shell variable to the awk pattern use the following syntax:
awk -v p="MC exp. sig-$p" '/p/ {print $10}' a.txt | tr -d '$'
More lines would've been nice but I guess you would like to have a simple use awk.
awk '{print $N}' $file
If you don't tell awk what kind of field-separator it has to use it will use just a space ' '. Now you just have to count how many fields you have got to get your field you want to get. In your case it would be 10.
awk '{print $10}' file.txt
$3.57
Don't want the $?
Pipe your awk result to cut:
awk '{print $10}' foo | cut -d $ -f2
-d will use the $ als field-separator and -f will select the second field.
If you know you always have the same number of fields, then
#!/bin/bash
file=$1
key=$2
while read -ra f; do
if [[ "${f[0]} ${f[1]} ${f[2]} ${f[3]}" == "MC exp. $key events" ]]; then
echo ${f[9]}
fi
done < "$file"