Shell

With “END” being just an example of any random string that must not appear in the commented section:

: << 'END'
sleep 1
END

${<variable>:-<default-value>}

Different options:

# option 1, without variable
for x in a b c; do echo $x; done
 
# option 2, with string
list="a b c"
for x in $list; do echo $x; done         # only works with sh and bash
for x in ${=list}; do echo $x; done      # only works with zsh
for x in $(echo $list}; do echo $x; done # works with any shell
 
# option 3, with an array
list=(a b c)
for x in $list; do echo $x; done

Use find, with {} being the file name:

find . -type f -exec <command> {} \;
find -iname "<pattern>" -exec <command> {} \;

Manual solution:

#!/bin/sh
 
function search_dir()
{
    DIR=$1;
 
    for file in $DIR/*; do
        if [[ -f $file ]]; then
            echo "Do something with $file"
        fi;
    done
 
 
    for element in $DIR/* ; do
        if [[ -e $element && -d $element && \
            $(basename "$element") != ".." && \
            $(basename "$element") != "." ]]; then
 
            search_dir "$element";
        fi;
    done;
}
 
search_dir "."