Bash syntax error when comparing a value with an array

Question

I have the following arrays defined in a bash script

IFS=, read -r -a start_files <<< $(head -n 1 file.txt)
IFS=, read -r -a end_files <<< $(tail -n 1 file.txt)

I read also two values from a file

micro=1000000
IFS=#

[ ! -f $INPUT ] && { echo "$INPUT file not found"; exit 99; }
while read start_time end_time
do

    start_time=$(bc <<< "scale=6; $start_time/$micro")
    end_time=$(bc <<< "scale=6; $end_time/$micro")

    ...

done < $INPUT
IFS=$OLDIFS

The values stored in the arrays and in start_time and end_time are epoch times, I mean values like 1361810326.840284000, 1361862515.600478000, 1361990369.166456000

In the "..." line I want to compare the values of start_time and end_time with all the values stored in an array in the following way

for i in `seq 0 116`;
do
    if [ $start_time -ge ${start_files[$i]} && $start_time -le ${end_files[$i]}]; then
        startF=$i
    fi        
done


for j in `seq 0 116`;
do
    if [ $end_time -ge ${start_files[$j]} && $end_time -le ${end_files[$j]}]; then
        endF = $j
    fi        
done

However this code yields a syntax error. What am I doing wrong?

Arguments to a command need to be separated by e.g. a space. — Ignacio Vazquez-Abrams, Oct 28 '14 at 17:08
It would be helpful if you indicated what your syntax error was in the question. — Tom Fenech, Oct 28 '14 at 17:09
You are missing a space before the closing `]` of the test `[`. — Etan Reisner, Oct 28 '14 at 17:09
What version of `bash` are you using? There is a bug, fixed in 4.3, that can cause problems when using pre-command assignments to `IFS` and reading from a here string at the same time. The result is that the here string is split into space-separate words on the embedded commas, but the entire space-separated string is placed in the first argument of the array, rather than one word per element. — chepner, Oct 28 '14 at 17:14
Re: my previous comment, see http://stackoverflow.com/a/20163550/1126841 — chepner, Oct 28 '14 at 17:26
Also, `-ge` and `-le` only work with integers. `bash` cannot the compare floating point values that are in `start_time` and `end_time` (and presumably those read from the file). — chepner, Oct 28 '14 at 17:51

Tom Fenech · Answer 1 · 2014-10-28T17:21:16.733

If you are using POSIX shell-style comparisons, it is good practice to put each test in its own square brackets. Also, you were missing a space from the end of the comparison. Remember that ] is an argument to the function [, rather than a syntactical construct:

for i in {0..116}; do
    if [ "$start_time" -ge "${start_files[$i]}" ] && [ "$start_time" -le "${end_files[$i]}" ]; then
        startF="$i"
    fi        
done

Same for the other one. I have quoted your variables as it is a good habit to get into. I have also used a brace expansion rather than calling seq.

If you are using bash, you can take advantage of the nicer arithmetic syntax:

for ((i=0; i<=116; ++i)); do
    if (( start_time >= ${start_files[$i]} && start_time <= ${end_files[$i]} )); then
        startF="$i"
    fi        
done

Bash syntax error when comparing a value with an array

1 Answers1