BASH command: How to save output of bash command into variable and later pipeline into command - bash

i have a question about how to store the output into variable and then later pipeline into another command
var=$(ps -auxc | grep -vE '^USER' )
#get top CPU
echo $var | sort -nr -k3 | head -1
#get top memory
echo $var | sort -nr -k4 | head -1


Make sure to use quotes in assignment and while accessing variable:
var="$(ps -auxc | grep -vE '^USER')"
#get top CPU
sort -nr -k3 <<< "$var" | head -1
#get top memory
sort -nr -k4 <<< "$var" | head -1


I'm not sure if this would always work:
IFS= read -rd '' var < <(ps -auxc | grep -vE '^USER') ## -d '' may be -d $'\0'
echo -n "$var" | sort -nr -k3 | head -1
However using readarray could:
readarray -t var < <(ps -auxc | grep -vE '^USER')
printf '%s\n' "${var[#]}" | sort -nr -k4 | head -1

Related

How to save the output of an sh to a Groovy variable?

I need to store the output of this command into a variable:
sh "curl -s 'http://nexus-cicd.stgcloud.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.xml' | grep '<version>.*</version>' | sort --version-sort | uniq | tail -n1 | sed -e 's#\\(.*\\)\\(<version>\\)\\(.*\\)\\(</version>\\)\\(.*\\)#\\3#g'"
I tried the following, but echo output null
parentLast = sh ("curl -s 'http://nexus-cicd.stgcloud.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx.xml' | grep '<version>.*</version>' | sort --version-sort | uniq | tail -n1 | sed -e 's#\\(.*\\)\\(<version>\\)\\(.*\\)\\(</version>\\)\\(.*\\)#\\3#g'")
echo "$parentLast"

Bash Script: Filter large files for value

I have several config files with around 20k lines each and I need to get some values from them.
I know that each of the values I need starts with a specific word "CONFNET" so I tried to get the values with a while loop, which reads every line.
But unfortunately this is extremely inefficient and slow.
Is there a better solution to this?
for filename in ~/configs/*; do
ip=$(cat $filename | strings | grep -i -A 7 "addnet_outside" | head -7 | grep "IP" | sed "s/IP//" | sed "s/=//" | sed -e 's/^[ \t]*//')
hostname=$(cat $filename | strings | grep -a "Inst:" | head -1 | sed "s/Inst://" | sed -e 's/^[ \t]*//')
while IFS= read -r line; do
object_name=$(echo $line | strings | grep "CONFNET" | sed "s/CONFNET//" | awk '{print $1}')
object_value=$(echo $line | strings | grep "CONFNET" | sed "s/CONFNET//" | awk '{print $3}' | sed -e 's/^[ \t]*//')
if [ ! -z $object_name ] && [ ! -z $object_value ]
then
echo $hostname "->" $object_name ":" $object_value
done < "$filename"
done

Shell Script do while flow

I have a script whose content is like:
#!/bin/bash
DB_FILE='pgalldump.out'
echo $DB_FILE
DB_NAME=''
egrep -n "\\\\connect\ $DB_NAME" $DB_FILE | while read LINE
do
DB_NAME=$(echo $LINE | awk '{print $2}')
STARTING_LINE_NUMBER=$(echo $LINE | cut -d: -f1)
STARTING_LINE_NUMBER=$(($STARTING_LINE_NUMBER+1))
TOTAL_LINES=$(tail -n +$STARTING_LINE_NUMBER $DB_FILE | \
egrep -n -m 1 "PostgreSQL\ database\ dump\ complete" | \
head -n 1 | \
cut -d: -f1)
tail -n +$STARTING_LINE_NUMBER $DB_FILE | head -n +$TOTAL_LINES > /backup/$DB_NAME.sql
done
I know what it is doing. But i have a doubt about the flow of do while in this case. At line egrep -n "\\\\connect\ $DB_NAME" $DB_FILE | while read LINE will egrep runs first or while . Because DB_NAME is empty at start of code.
Could anyone please explain the flow of do while in this case.

Scale in associative arrays

I'm trying to print an associative array with decimals but I don't know the way to do it:
#!/bin/bash
quantity="quantity.csv"
line=20
declare -A addQuantity
declade -A average
declare -A numberOfQuantity
for i in `seq 2 $line`
do
name=`cat $quantity | sort -n -k2 -t"," | head -n$i | tail -n1 | cut -d ',' -f4`
quantity=`cat $quantity | sort -n -k2 -t"," | head -n$i | tail -n1 | cut -d ',' -f5`
addQuantity[$name]=$((addQuantity[$name]+quantity))
numberOfQuantity[$name]=$((numberOfQuantity[$name]+1))
done
for i in `seq 2 $line`
do
name=`cat $quantity | sort -n -k2 -t"," | head -n$i | tail -n1 | cut -d ',' -f4`
average[$name]=$((addQuantity[$name]/numberOfQuantity[$name]))
echo "$name - $quantity - ${addQuantity[$name] - $ {numberOfQuantity[$name]} - ${average[$name]}"
done
This works good but I want to print the average with decimals.
My file .csv is that:
[...],[...],[...],name,quantity
0,0,0,name1,4
0,0,0,name1, 7
0,0,0,name2,10
0,0,0,name3,4
0,0,0,name3,6

Using bash command on a variable that will be used as reference for an array

Short and direct, basically I want to use the value of $command on a variable, instead using it inside the while loop as a command itself. So:
This Works, but I think it's ugly:
#!/bin/bash
IFS=$'\n'
lsof=`which lsof`
whoami=`whoami`
while true ; do
execution_array=($(${lsof} -iTCP -P 2> /dev/null | grep ':' | grep ${whoami} | awk '{print $9}' | cut -f2 -d'>' | sort | uniq ))
for i in ${execution_array[*]}; do
echo $i
done
sleep 1
done
unset IFS
This doesn't work ( no output happens ), but i think is less ugly:
#!/bin/bash
IFS=$'\n'
lsof=`which lsof`
whoami=`whoami`
command="${lsof} -iTCP -P 2> /dev/null | grep ':' | grep ${whoami} | awk '{print $9}' | cut -f2 -d'>' | sort | uniq"
while true ; do
execution_array=($(command))
for i in ${execution_array[*]}; do
echo $i
done
sleep 1
done
unset IFS

This solved my problem:
#!/bin/bash
IFS=$'\n'
lsof=$(which lsof)
list_connections() {
${lsof} -iTCP -P 2> /dev/null | grep ':' | grep $(whoami) | awk '{print $9}' | cut -f2 -d'>' | sort | uniq
}
while true ; do
execution_array=($(list_connections))
for i in ${execution_array[*]}; do
echo $i
done
sleep 1
done
unset IFS

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