Check if directory exists and count files matching a pattern in it [duplicate]

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My code has a directory path incoming, e.g., $D_path from a source.

$D_path

Now I need to check if the directory path exists and the count of files with a pattern (*abcd*) in that path exists or not in an IF Condition.

*abcd*

I do not know how to use such complex expressions through bash Scripting.

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1 Answer
1

A code-only answer. Explanations available upon request

if [[ -d "$D_path" ]]; then
files=( "$D_path"/*abcd* )
num_files=$#files[@]
else
num_files=0
fi


I forgot this: by default if there are no files matching the pattern, the files array will contain one entry with the literal string *abcd*. To have the result where the directory exists but no files match => num_files == 0, then we need to set an additional shell option:

files

*abcd*

shopt -s nullglob


This will result in a pattern that matches no files to expand to nothing. By default a pattern that matches no files will expand to the pattern as a literal string.

$ cat no_such_file
cat: no_such_file: No such file or directory
$ shopt nullglob
nullglob off

$ files=( *no_such_file* ); echo "$#files[@]"; declare -p files
1
declare -a files='([0]="*no_such_file*")'

$ shopt -s nullglob

$ files=( *no_such_file* ); echo "$#files[@]"; declare -p files
0
declare -a files='()'