Shell script, saving the command value to a variable [duplicate]

Question

I am trying to print the value of VARI in the same line followed by a comma, so that i can have a csv file of these values, but i m not able to save the value of VARI = 'cat filename | head -1 | cut -d, -f${i}'

i=0
while (( i<130)) ;
do
  if [[ $i -eq 1 ||  $i -eq 9 || $i -eq 12 || $i -eq 23 || $i -eq 25 || $i -eq 29 ]]
  then
    VARI = 'cat filename | head -1 | cut -d, -f${i}'
    echo  "$VARI ,"   
  fi
  let i=$i+1;
done

output expected is

4,abc,5,8,xyz,9

Please let me know what i am doing wrong, thanks!

I don't know how to put back quote. But In VARI the line should have back quote — badawi
– badawi, Commented Aug 5, 2011 at 15:45
@badawi -- tried it, does not work..first.sh: line 8: VARI = cat filename | head -1 | cut -d, -f${i}: command not found — learner
– learner, Commented Aug 5, 2011 at 15:48
@badawi: VARI = `cat filename | head -1 | cut -d, -f${i}` :) — knittl
– knittl, Commented Aug 5, 2011 at 15:49
first.sh: line 8: VARI: command not found.. am i missing something? — learner
– learner, Commented Aug 5, 2011 at 15:54

knittl · Accepted Answer · 2023-10-18 05:28:39Z

13

Use backticks (or $() which can be nested), not single quotes:

VARI=`cat filename | head -1 | cut -d, -f${i}` # or:
VARI=$(cat filename | head -1 | cut -d, -f${i})

Make sure to not have spaces between the variable name, the equal sign, and the variable value.

VAR = x # executes program "VAR" with 2 parameters: "=" and "x"
VAR =x  # executes program "VAR" with a single parameter: "=x"
VAR= x  # executes program "x" with environment variable "VAR" set to an empty value
VAR=x   # assigns value "x" to shell variable "VAR"

Resources: 2.10.2 Shell Grammar Rules of the POSIX.1-2017 specification.

edited Oct 18, 2023 at 5:28

answered Aug 5, 2011 at 15:47

knittl

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2 Comments

learner Over a year ago

first.sh: line 8: VARI: command not found.. am i missing something?

learner Over a year ago

Awesome.. thanks! .. works!.. such silly mistake!.. did not realise the importance of space ;)

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