How to iterate over positional parameters in a Bash script?

Question

Where am I going wrong?

I have some files as follows:

filename_tau.txt
filename_xhpl.txt
filename_fft.txt
filename_PMB_MPI.txt
filename_mpi_tile_io.txt         


        

Answer 1

See here, you need shift to step through positional parameters.

Answer 2

args=$@;args=${args// /,}
grep "foo" $(eval echo file{$args})

Answer 3

There is more than one way to do this and, while I would use shift, here's another for variety. It uses Bash's indirection feature:

#!/bin/bash
for ((i=1; i<=$#; i++))
do
    grep "$str" ${filename}${!i}.txt
done

One advantage to this method is that you could start and stop your loop anywhere. Assuming you've validated the range, you could do something like:

for ((i=2; i<=$# - 1; i++))

Also, if you want the last param: ${!#}

Answer 4

Set up your for loop like this. With this syntax, the loop iterates over the positional parameters, assigning each one to 'point' in turn.

for point; do
  grep "$str" ${filename}${point}.txt 
done

Answer 5

Try something like this:

# Iterating through the provided arguments
for ARG in $*; do
    if [ -f filename_$ARG.txt]; then
        grep "$str" filename_$ARG.txt 
    fi
done