Awk with while loop in bash?

Question

I have one question about my script.

I have this kind of csv file to process with my script :

RXK7;MIAO24;Running;Linux;24;16;32;DefaultPool;shared
RXK6;MIAO24;Running;Linux;24;16;32;DefaultPool;shared
RXK4;MIAO24;Running;Linux;24;16;32;DefaultPool;shared
RXK1;MIAO24;Running;Linux;24;16;32;DefaultPool;shared
RXK2;MIAO24;Running;Linux;24;16;32;DefaultPool;shared
RXK5;MIAO24;Running;Linux;24;16;32;DefaultPool;shared
RXK3;MIAO24;Running;Linux;24;16;32;DefaultPool;shared

I want to keep only the 1,2,5,6 and 7 columns. To do that, I use this command :

cat test.csv | awk -F',|;' '{print $1","$2","$5","$6","$7}'

And the result is :

RXK7,MIAO24,24,16,32
RXK6,MIAO24,24,16,32
RXK4,MIAO24,24,16,32
RXK1,MIAO24,24,16,32
RXK2,MIAO24,24,16,32
RXK5,MIAO24,24,16,32
RXK3,MIAO24,24,16,32

With my script :

#!/bin/bash

OLDIFS=$IFS
IFS=','


for arg
do

    echo "File :" $arg | cut -d'.' -f1
    echo "======================================================="
    echo ""

    while read FRAME LPARS RAM CPU1 CPU2
    do
        if [[ $FRAME != $PREV ]]
        then
            PREV=$FRAME
            echo "FRAME : $FRAME"
            echo -e "-----------------\n"
        fi
        echo -e "LPARS :\t$LPARS\n\
RAM : \t$RAM\n\
CPU 1 :\t$CPU1\n\
CPU 2 :\t$CPU2\n"
        echo ""
    done < "$arg"
done

I can display theses informations of my differents csv like that :

File : test2
=======================================================

LPARS : 
RAM :   
CPU 1 : 
CPU 2 : 


FRAME : RXK7
-----------------

LPARS : MIAO24
RAM :   24
CPU 1 : 16
CPU 2 : 32


FRAME : RXK6
-----------------

LPARS : MIAO24
RAM :   24
CPU 1 : 16
CPU 2 : 32


FRAME : RXK4
-----------------

LPARS : MIAO24
RAM :   24
CPU 1 : 16
CPU 2 : 32


FRAME : RXK1
-----------------

LPARS : MIAO24
RAM :   24
CPU 1 : 16
CPU 2 : 32


FRAME : RXK2
-----------------

LPARS : MIAO24
RAM :   24
CPU 1 : 16
CPU 2 : 32


FRAME : RXK5
-----------------

LPARS : MIAO24
RAM :   24
CPU 1 : 16
CPU 2 : 32


FRAME : RXK3
-----------------

LPARS : MIAO24
RAM :   24
CPU 1 : 16
CPU 2 : 32

But this is possible only if I create a temporary file beforehand :

cat test.csv | awk -F',|;' '{print $1","$2","$5","$6","$7}' > test2.csv

I want to know if it's possible to do this without the need to create a temporary file ? I think something like :

for arg
do

    echo "File :" $arg | cut -d'.' -f1
    echo "======================================================="
    echo ""

    cat $arg | awk -F',|;' '{print $1","$2","$5","$6","$7}' | while read FRAME LPARS RAM CPU1 CPU2
    do
        if [[ $FRAME != $PREV ]]
        then
            PREV=$FRAME
            echo "FRAME : $FRAME"
            echo -e "-----------------\n"
        fi
        echo -e "LPARS :\t$LPARS\n\
RAM : \t$RAM\n\
CPU 1 :\t$CPU1\n\
CPU 2 :\t$CPU2\n"
        echo ""
    done < "$arg"
done

Or maybe it's possible to do this only with awk ?

Thank you for your help !

Personally, I would do it with just awk, since awk can also print \t and \n. Or I would use Perl :) . Anyway, if you remove the < "$arg" after done, I think the code you have might actually work. Edit and in the awk code, change "," to " ". — cxw
– cxw, Commented Jul 12, 2019 at 10:11
It is very easy to do with awk alone awk -F',|;' '{ print "\nFRAME:",$1; print "==================="; print "\nLPARS:",$2; print "\nRAM:",$5; print "\nCPU1:",$6; print "\nCPU:",$7 }' input.txt — j23
– j23, Commented Jul 12, 2019 at 10:17

Poshi · Accepted Answer · 2019-07-12 10:12:48Z

2

You can use dummy read values, so you don't have to cut your columns:

while read FRAME LPARS _ _ RAM CPU1 CPU2
do
    # Things
done < "$arg"

You can also use the code you provided. Is it not working?

Also, I would advise you to use cut instead of awk for those simple situations, as cut is a lot lightweigth than awk:

cut -d; -f1,2,5-7 test.csv

And clearly, it is possible and easier to do only with awk.

answered Jul 12, 2019 at 10:12

Poshi

5,8633 gold badges22 silver badges37 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Makmy Over a year ago

What do you mean by " dummy read values ? " I can do : while read FRAME LPARS _ _ RAM CPU1 CPU 2; do ###; done <"$arg" And the " _ _ " are the 3 and 4 columns ?

Poshi Over a year ago

Yes. Those placeholders will take the values that you are not interested in.

Collectives™ on Stack Overflow

Awk with while loop in bash?

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related