+save_sample() {
+    # Usage: save_sample arg1
+    # Input: arg1   list_paths        (list of files to take samples from)
+    #        envvar BKFEH_SAMPLE_DIR  (environment variable set outside of this script)
+    #        envvar BKFEH_SAMPLE_SIZE (space limit for sample dir files)
+    # Depends: GNU Parallel, GNU find, GNU Coreutils 8.32 (cut, find, du)
+    #   BK-2020-03: bkshuf (0.0.1), yell()
+    local list_paths
+    sample_count="100"; # max number of images to put in sample dir
+    sample_max_space="10000000"; # max bytes to put in sample dir
+
+    # Load environment variables if set
+    if [[ ! -v BKFEH_SAMPLE_DIR ]]; then return 0; fi; # return early if environment var not set.
+    if [[ -v BKFEH_SAMPLE_SIZE ]] && checkInt "$BKFEH_SAMPLE_SIZE"; then
+        sample_max_space="$BKFEH_SAMPLE_SIZE";
+    fi;
+    if [[ -v BKFEH_SAMPLE_COUNT ]] && checkInt "$BKFEH_SAMPLE_COUNT"; then
+        sample_count="$BKFEH_SAMPLE_COUNT";
+    fi;
+    
+    if [[ -n "$1" ]]; then
+        list_paths="$1"; # newline-delimited list of file paths to sample from
+    else
+        yell "ERROR:NO paths available to sample.";
+    fi;
+    
+    if [[ -d "$BKFEH_SAMPLE_DIR" ]]; then
+        #sample_dir="$BKFEH_SAMPLE_DIR";
+        yell "STATUS:Environment variable BKFEH_SAMPLE_DIR set. Clearing and saving samples...";
+        
+        ## clear previous sample
+        count_prev_samples="$(find "$BKFEH_SAMPLE_DIR" -maxdepth 1 -type f | wc -l)";
+        yell "STATUS:Deleting $count_prev_samples previous samples...";
+        find "$BKFEH_SAMPLE_DIR" -maxdepth 1 -type f -exec rm '{}' \; ;
+        
+        ## save random sample
+        yell "STATUS:Saving random sample of size $sample_count to $BKFEH_SAMPLE_DIR...";
+        list_paths_sample="$(echo "$list_paths" | bkshuf "$sample_count" | head -n"$sample_count")";
+        n_samp=0; # init sample file counter
+        sample_log="$BKFEH_SAMPLE_DIR"/paths.txt;
+        printf "%s,%s,%s\n" "n_samp" "file_hash" "file_path" >> "$sample_log";
+        while read -r line; do
+            if [[ -z "$line" ]]; then continue; fi;
+            ### check size limit
+            sample_act_space="$(du -bd1 "$BKFEH_SAMPLE_DIR" | cut -f1 )"; # actual used space
+            cand_space="$(du -bd1 "$line" | cut -f1 )"; # size of candidate file to add
+            sample_req_space="$((sample_act_space + cand_space))";
+
+            ### Customize file names
+            n_samp_w="$(printf "%s" "$sample_count" | wc -c)";
+            n_samp_fmt="%0""$n_samp_w""d";
+            n_samp_dd="$(printf "$n_samp_fmt" "$n_samp")"; # sample number fixed-width
+            file_path="$line";
+            #file_dir="$(dirname "$line")";
+            file_name="$(basename "$line")";
+            file_hash="$(b2sum -l32 "$line" | awk '{print $1}')"; # use file hash to avoid clobbering
+            file_ext="${file_name##*.}";
+            file_name="${file_name%.*}";
+            file_shortname="${file_name:0:32}";
+            file_name_new="$n_samp_dd"_"$file_hash".."$file_shortname"."$file_ext";
+            file_path_new="$BKFEH_SAMPLE_DIR"/"$file_name_new"            
+            if [[ "$sample_req_space" -lt "$sample_max_space" ]]; then
+                #### add file to sample dir
+                must cp -n "$file_path" "$file_path_new";
+                #### note path in sample dir log
+                printf "%s,%s,%s\n" "$n_samp_dd" "$file_hash" "$file_path" \
+                       >> "$sample_log";
+            fi;
+            ((n_samp++));
+        done < <( echo "$list_paths_sample" );
+    else
+        yell "ERROR:Does not exist: $BKFEH_SAMPLE_DIR";
+    fi;    
+}; # save sample of files
+