bash script to iterate from middle of a list - bash

Question

I have a bash script that iterates over a folder of sql scripts. I want it to run intelligently when the script encounters an error. I don't want to run a step twice.
for a in $files_list; do
command 1
command 2
.
.
done
If 1,2,3,4,5 are the files to be executed and script exits at step 3 with some error. In next execution, I want to run from step 3 only. I have a variable in place for detecting at which step the script exited. I am stuck at starting the iteration from that variable.
Is it something that can be done? Any suggestion is accepted. I'm open to change my logic as well.

Answer 1

Didn't really spend much time but Let's say all the commands you want to execute are stored in a file test.txt
test.txt
ls
cal
du
d
date
ls
The following bash script takes two arguments filename where the commands are stored and the checkpoint from where it needs to start.
test.sh
## Function to read a file line by line
checkpoint=$2
filename=$1
checkpointReached=false
read_file_line_by_line() {
local file="$1"
while IFS= read -r line
do
if [ $checkpointReached == "false" ] && [ "$line" != "$checkpoint" ] ; then
echo "...... Finding checkpoint....... current line is $line"
fi
if [ "$line" == "$checkpoint" ]; then
echo " *************************************************
Checkpoint reached. Commands after checkpoint
*****************************************************"
checkpointReached=true
continue
fi
if $checkpointReached; then
echo " $line"
execute_command $line
fi
done < "$file"
}
function execute_command() {
local command="$1"
echo " Executing .......... $command"
if eval $command; then
echo " Command executed successfully"
else
echo " Command failed. Exiting........"
echo " Please note the new checkpoint.... $command"
exit 1
fi
}
read_file_line_by_line "$filename"
Let's run it the first time, the checkpoint is the first command i.e. ls and its expected to fail at d which is invalid command
╰─ bash test.sh text.txt "ls"
*************************************************
Checkpoint reached. Commands after checkpoint
*****************************************************
Executing .......... ls
test.sh test.yaml text.txt
Command executed successfully
du
Executing .......... du
24 .
Command executed successfully
d
Executing .......... d
test.sh: line 33: d: command not found
Command failed. Exiting........
Please note the new checkpoint.... d
Now we know the checkpoint. So we pass it along. Assuming that d is fixed now, we change it with echo for the sake of the script. In your case the script d would be fixed.
╰─ bash test.sh text.txt "echo"
...... Finding checkpoint....... current line is ls
...... Finding checkpoint....... current line is du
*************************************************
Checkpoint reached. Commands after checkpoint
*****************************************************
Executing .......... echo
Command executed successfully
date
Executing .......... date
Mon Sep 12 14:50:44 +04 2022
Command executed successfully
Let me know if this helps.