Search a file column wise and delete it

Shell Programming and Scripting
1

Scottn, m really sorry but i have not got my answer yet.
my concern is how to delete the row !!!
i have a file which has a column that is unique
i am intending to serach it and if it is there to remove the row.

the file looks like

 
ROLLNO,NAME ,SUB1,SUB2,SUB3,TOTAL,PERCENTAGE,RESULT
15 ,rig ,34 ,56 ,87 ,177 ,59 % ,PASS
23 ,wel ,45 ,76 ,56 ,177 ,59 % ,PASS
24 ,rew ,23 ,45 ,67 ,135 ,45 % ,THIRD

if i need to remove the row with a roll num
i have tried with

 
cut -f1 -d "," studentrec.txt | sed '/"$rollno"/d'
even with 
cut -f1 -d "," studentrec.txt | sed '/"$rollno"/{d;}'

but still unable to get the required result

plz help

2

Try,

$ awk -F ',' -v rnum=15 '$1 == rnum { next }1' studentrec.txt

$ rnum=23;sed  '/^'$rnum'/d' studentrec.txt
3

gotam,

If you want to delete always the row/rows containing "rollno" try with:

grep -v -i rollno inputfile

regards

4

Hi,

Try this,

grep -v "^$roll_no" stundent.txt
5

i tried all of ur suggestions

this is not helping me to permanently delete the intended row.
rather.. at the time i am pursuing the command it helps me to hide the intended rows and output the rest
but againn when i am doing all rows are coming intact.

Plz help me to delete the rows permanently from the file !!!

6

Hi,

write the output of the command to temp file and rename (mv) the temp file with stundent.txt.

grep -v "^$roll_number" stundent.txt > temp ; mv temp stundent.txt
7

Hi.

If your sed supports the -i option:

sed -i "/^$rollnum[ ,]/d" file1

Otherwise you can use ed:

ed file1 << !
/^$rollnum[ ,]/d
w
q
!

Otherwise, create a temporary file, as shown in previous suggestions.

8

Thanks..
i got it working..

sed -i is not working .. not sure why!!
but the one suggested by praveen serves the purpose though it requires a temp file.

thank you all !!

9

Not all SEDs have the -i option (in fact very few of them do!)

The pravin27 solution will fail for three-digit roll numbers where the first two numbers are not unique:

i.e

23
230

You should modify it slightly.

10

yes thats true !!
i was happy assuming that it got resolved
you made me to fry my brain again .
thanks for pointing that out !! i'll work on it and post the finding :slight_smile: