Parse name value pairs in csv line using shell script - parsing

Question

I have input which looks like the following 2 lines:
TASK1,6,INITIAL,2013-01-15 19:20:40,PREPARING,2013-01-15 19:21:12,SCHEDULED,2013-01-15 19:21:13,TRANSLATING,2013-01-15 19:21:13,LOADING,2013-01-15 19:36:37,COMPLETE,2013-01-15 19:36:42
TASK2,5,INITIAL,2013-01-15 19:20:44,PREPARING,2013-01-15 19:21:13,SCHEDULED,2013-01-15 19:21:14,TRANSLATING,2013-01-15 19:36:37,TERMINAL,2013-01-15 20:28:10
I need to loop through a file with these lines and for each line calculate several time differences... i'm fine on the calculations and such, but i'm having a devil of a time trying to figure out how to parse this "variable length" string of name value pairs...
Basically the # after the Task# is the count of "statuses" followed by those statuses and their occuring time.
What i'd like to do is get one of the lines and end up with something like this having the values assigned to their respective variables. (using first line as example):
$TASK_ID=TASK1
$STATUS_COUNT=6
$INITIAL=2013-01-15 19:20:40
$PREPARING=2013-01-15 19:21:12
$SCHEDULED=2013-01-15 19:21:12
$TRANSLATING=2013-01-15 19:21:13
$LOADING=2013-01-15 19:36:37
$COMPLETE=2013-01-15 19:36:42
$TERMINAL=<NULL>
Compounding the problem is that if a task is submitted more than once it will simply append the next round of statuses to the first set meaning i could end up with an input line like:
TASK1,11,INITIAL,2013-01-15 19:20:40,PREPARING,2013-01-15 19:21:12,SCHEDULED,2013-01-15 19:21:13,TRANSLATING,2013-01-15 19:21:13,LOADING,2013-01-15 19:36:37,COMPLETE,2013-01-15 19:36:42,INITIAL,2013-01-15 20:20:40,PREPARING,2013-01-15 20:21:12,SCHEDULED,2013-01-15 20:21:13,TRANSLATING,2013-01-15 20:21:13,TERMINAL,2013-01-15 20:36:42
I this case i would want my output to be:
$TASK_ID=TASK1
$STATUS_COUNT=11
$INITIAL=2013-01-15 20:20:40
$PREPARING=2013-01-15 20:21:12
$SCHEDULED=2013-01-15 20:21:12
$TRANSLATING=2013-01-15 20:21:13
$LOADING=<NULL>
$COMPLETE=<NULL>
$TERMINAL=2013-01-15 20:36:42
I'm pretty stumped on this, can anyone help?
Thanks in advance

Answer 1

#!/bin/bash
# Splitting on commas, read the task ID and status count followed by all of the statuses,
# which we'll parse later.
while IFS=, read -r TASK_ID STATUS_COUNT STATUSES; do
(
# Subtly, but importantly, we put the loop body inside parentheses so each loop
# iteration runs in a sub-shell. This ensures that the $LOADING, $COMPLETE, etc.
# variables we set don't leak into future iterations.
echo "TASK_ID = $TASK_ID"
echo "STATUS_COUNT = $STATUS_COUNT"
# Convert the comma-separated string $STATUSES into an array using `read -a'.
IFS=, read -ra STATUSES <<< "$STATUSES"
# Assign the statuses to named variables. A side benefit of this is that only the
# last value of each status type is used.
for ((i = 0; i < ${#STATUSES[#]}; i += 2)); do
declare "${STATUSES[$i]}=${STATUSES[$((i+1))]}"
done
# Print each of the statuses, or <NULL> if that stage wasn't listed.
echo "INITIAL = ${INITIAL:-<NULL>}"
echo "PREPARING = ${PREPARING:-<NULL>}"
echo "SCHEDULED = ${SCHEDULED:-<NULL>}"
echo "TRANSLATING = ${TRANSLATING:-<NULL>}"
echo "LOADING = ${LOADING:-<NULL>}"
echo "COMPLETE = ${COMPLETE:-<NULL>}"
echo "TERMINAL = ${TERMINAL:-<NULL>}"
echo
)
done
Output:
$ ./tasks < tasks.txt
TASK_ID = TASK1
STATUS_COUNT = 6
INITIAL = 2013-01-15 19:20:40
PREPARING = 2013-01-15 19:21:12
SCHEDULED = 2013-01-15 19:21:13
TRANSLATING = 2013-01-15 19:21:13
LOADING = 2013-01-15 19:36:37
COMPLETE = 2013-01-15 19:36:42
TERMINAL = <NULL>
TASK_ID = TASK2
STATUS_COUNT = 5
INITIAL = 2013-01-15 19:20:44
PREPARING = 2013-01-15 19:21:13
SCHEDULED = 2013-01-15 19:21:14
TRANSLATING = 2013-01-15 19:36:37
LOADING = <NULL>
COMPLETE = <NULL>
TERMINAL = 2013-01-15 20:28:10
TASK_ID = TASK1
STATUS_COUNT = 11
INITIAL = 2013-01-15 20:20:40
PREPARING = 2013-01-15 20:21:12
SCHEDULED = 2013-01-15 20:21:13
TRANSLATING = 2013-01-15 20:21:13
LOADING = 2013-01-15 19:36:37
COMPLETE = 2013-01-15 19:36:42
TERMINAL = 2013-01-15 20:36:42
(Glenn Jackman adding edit based on new requirement)
events=(INITIAL PREPARING SCHEDULED TRANSLATING LOADING COMPLETE TERMINAL)
while IFS=, read -r TASK_ID STATUS_COUNT rest; do
IFS=, read -ra STATUSES <<< "$rest"
for (( i=0; i < ${#STATUSES[#]}; i+=2 )); do
# if this this the initial event, reset all statuses
if [[ ${STATUSES[i]} == ${events[0]} ]]; then
for event in "${events[#]}"; do
declare "$event="
done
fi
declare "${STATUSES[i]}=${STATUSES[i+1]}"
done
for var in TASK_ID STATUS_COUNT "${events[#]}"; do
printf "$%s = %s\n" $var "${!var:-<NULL>}"
done
done