Bash script for automating HPC calculations

Question

I'm a chemistry student working on a simple bash script to automate HPC density functional theory calculations using Quantum Espresso (pw.x). I am very much a novice at shell scripting and would appreciate some criticism/feedback before I try to implement it on the cluster. The script calls in-gen.py which is a Python script I wrote for generating new input files if certain parameter thresholds in the log file are not met.

#!/bin/bash
    
#SBATCH --job-name=2x2x6_PbCO3          # job name        
#SBATCH --output=slurm.out              # Output file name                                                                                                                                                
#SBATCH --error=slurm.err               # Error file name                                                                                                                                                 
#SBATCH --partition=batch               # Partition                                                                                                                                                       
#SBATCH --qos=medium+                   # Queue                                                                                                                                                           
#SBATCH --time=24:00:00                 # Time limit                                                                                                                                                      
#SBATCH --nodes=3                       # Number of nodes                                                                                                                                                 
#SBATCH --ntasks-per-node=16            # MPI processes per node 

errors='MPI_ABORT|error|aborted|SIGTERM|TIME|CANCELLED|SIGCONT|terminated|fork'
job='2x2x6_PbCO3'
max_runs=5
prefix=PbCO3

#-------------------------------------------------------------------------------
Clear () 
{
# Checks for input/log from a completed batch script
if [[ -f "$prefix.in" && -f "$prefix.log"  ]]; then
   # If both are found a new input file is generated
   python ~/path-to-in-gen.py $prefix.log $prefix.in $job override
   if [ -z "$(ls -A ../logs_and_inputs)" ]; then
      index=1
   else
      indices=()
      # Old input/log are tagged and stored
      for entry in "../logs_and_inputs"/$prefix.in-*; do
         indices+=("${entry: -1}")
      done
      max=${indices[0]}
      for n in "${indices[@]}" ; do
         ((n > max)) && max=$n
      done
      index=$((max+1))
      rm -r *x*x*
      mv $prefix.in ../logs_and_inputs/$prefix.in-$index
      mv $prefix.log ../logs_and_inputs/$prefix.log-$index
      mv $prefix.in-new $prefix.in
   fi
fi
}
#-------------------------------------------------------------------------------
# Creates a directory for old logs and inputs to be stored with a numerical tag from 1 to k
Sort ()
{
if [ ! -d "../logs_and_inputs" ]; then
    mkdir ../logs_and_inputs
    iter=1
else
   if [ -z "$(ls -A ../logs_and_inputs)" ]; then
      iter=1
   else
      indices=()
      for entry in "../logs_and_inputs"/$prefix.in-*; do
         indices+=("${entry: -1}")
      done
      max=${indices[0]}
      for n in "${indices[@]}" ; do
         ((n > max)) && max=$n
      done
      iter=$((max+1))
   fi
fi
max_iter=$((iter+max_runs))
}
#-------------------------------------------------------------------------------                                                                                                   
Automode () 
{
mpirun ~/path-to-pw.x < $prefix.in > $prefix.log
# Runs pw.x job, checks for completion and errors
if grep -E -q -- $errors "slurm.err"; then 
   exit 1
fi
if grep -q "job DONE." "$prefix.log"; then
   # Clear wavefunction files and temp directories
   rm -r *x*x*
   # Generates new input file
   python ~/path-to-in-gen.py $prefix.log $prefix.in $job
   # Tags and stores the previous input and log
   mv $prefix.in ../logs_and_inputs/$prefix.in-$iter
   mv $prefix.log ../logs_and_inputs/$prefix.log-$iter
else
   exit 1
fi
   # Checks for generation of new input file
if test -f "$prefix.in-new"; then
   mv $prefix.in-new $prefix.in
else
   exit 1
fi
let "iter=iter+1"
}
#-------------------------------------------------------------------------------                                                                                                   
Clear

Sort

while ((iter < max_iter)); do
   Automode
done

Answer 1

Specific suggestions:

1. Function names are by convention snake_case.
2. Use More Quotes™.
3. [[ should be used instead of [, because it's safer.
4. [[ EXPRESSION ]] && [[ EXPRESSION ]] would be clearer than [[ EXPRESSION && EXPRESSION ]], in my opinion.
5. set -o errexit -o noclobber -o nounset -o pipefail and shopt -s globfail would make the error handling much stricter.
6. This is no longer trivial code, so I'd recommend implementing it in a non-shell language like Python.

Tool suggestions:

1. Running shellcheck on your script regularly is a good way to capture possible issues. In this case the only thing it finds is for rm -r *x*x*:

   SC2035: Use ./glob or -- glob so names with dashes won't become options.