Loop through an array of strings in Bash?

Question

I want to write a script that loops through 15 strings (array possibly?) Is that possible?

Something like:

for databaseName in listOfNames
then
  # D         


        

Answer 1

Implicit array for script or functions:

In addition to anubhava's correct answer: If basic syntax for loop is:

for var in "${arr[@]}" ;do ...$var... ;done

there is a special case in bash:

When running a script or a function, arguments passed at command lines will be assigned to $@ array variable, you can access by $1, $2, $3, and so on.

This can be populated (for test) by

set -- arg1 arg2 arg3 ...

A loop over this array could be written simply:

for item ;do
    echo "This is item: $item."
  done

Note that the reserved work in is not present and no array name too!

Sample:

set -- arg1 arg2 arg3 ...
for item ;do
    echo "This is item: $item."
  done
This is item: arg1.
This is item: arg2.
This is item: arg3.
This is item: ....

Note that this is same than

for item in "$@";do
    echo "This is item: $item."
  done

Then into a script:

#!/bin/bash

for item ;do
    printf "Doing something with '%s'.\n" "$item"
  done

Save this in a script myscript.sh, chmod +x myscript.sh, then

./myscript.sh arg1 arg2 arg3 ...
Doing something with 'arg1'.
Doing something with 'arg2'.
Doing something with 'arg3'.
Doing something with '...'.

Same in a function:

myfunc() { for item;do cat <<<"Working about '$item'."; done ; }

Then

myfunc item1 tiem2 time3
Working about 'item1'.
Working about 'tiem2'.
Working about 'time3'.

Answer 2

You can use it like this:

## declare an array variable
declare -a arr=("element1" "element2" "element3")

## now loop through the above array
for i in "${arr[@]}"
do
   echo "$i"
   # or do whatever with individual element of the array
done

# You can access them using echo "${arr[0]}", "${arr[1]}" also

Also works for multi-line array declaration

declare -a arr=("element1" 
                "element2" "element3"
                "element4"
                )

Answer 3

This is also easy to read:

FilePath=(
    "/tmp/path1/"    #FilePath[0]
    "/tmp/path2/"    #FilePath[1]
)

#Loop
for Path in "${FilePath[@]}"
do
    echo "$Path"
done

Answer 4

What I really needed for this was something like this:

for i in $(the_array); do something; done

For instance:

for i in $(ps -aux | grep vlc  | awk '{ print $2 }'); do kill -9 $i; done

(Would kill all processes with vlc in their name)

Answer 5

None of those answers include a counter...

#!/bin/bash
## declare an array variable
declare -a array=("one" "two" "three")

# get length of an array
arraylength=${#array[@]}

# use for loop to read all values and indexes
for (( i=1; i<${arraylength}+1; i++ ));
do
  echo $i " / " ${arraylength} " : " ${array[$i-1]}
done

Output:

1  /  3  :  one
2  /  3  :  two
3  /  3  :  three

Answer 6

Possible first line of every Bash script/session:

say() { for line in "${@}" ; do printf "%s\n" "${line}" ; done ; }

Use e.g.:

$ aa=( 7 -4 -e ) ; say "${aa[@]}"
7
-4
-e

May consider: echo interprets -e as option here