liquidsword92 liquidsword92 - 1 year ago 68
Bash Question

Bash: Compare each line in for loop

I have a shell script that needs to analyze data from a file which looks like the following:

255 48 48 exp1
97 97 97 exas
238 44 44 dkopkw
194 194 194 sdkaok

I then take the data and sort it in a for statement. For each line I need to compare the data and see if it less than 90 and prints a line between the numbers.


for line in "$(sort /myfile.txt -k1 -n)"

COL_ONE=$(print "line" | awk '{print $1}')

if [[ $COL_ONE -lt 90 ]]; then
echo "$line"
echo "------------------"
echo "$line"


However, when this runs it does not print the line between the numbers. I want my output to look like the following:

97 97 97 exas
194 194 194 sdkaok
238 44 44 dkopkw
255 48 48 exp1

I am not sure what I am doing wrong and has been driving me insane.

Answer Source

A solution that bypasses the problems with your attempt and is more robust and efficient:

sort -k1,1 -n myfile.txt | awk '$1 < 98 { print $0 "\n------------------"; next } 1'

Note that I've used 98 rather than 90 as the comparison value, to be consistent with your desired output.
Also, note the ,1 added to -k1 to ensure that sorting is truly limited to the 1st field.

As for what you've tried:

Leaving efficiency issues, the 98 vs. 90 issue, and ill-advised practices aside:

  • If you double-quote a command substitution ("$(...)") its output is treated as a single input to the for loop.

  • print is not a Bash command (nor likely to be the name of an external utility, and "line" should be "$line" in order to reference the variable.

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