feat(user/bkfeh):Save up to 100MB or 100 sample images if envvar set

- Note: Environment variable is BKFEH_SAMPLE_DIR in which contents
  will be deleted and sample images saved upon every run of bkfeh.

diff --git a/user/bkfeh b/user/bkfeh
index 7dbf9fb067916155befd05c2d64fc050d5e719ec..c0410ef06308dc36f2e13012a344278208c5e742 100755 (executable)
--- a/user/bkfeh
+++ b/user/bkfeh
@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# Version: 0.0.7
+# Version: 0.1.0
 # Ref/Attrib: [1] Tange, Ole. GNU Parallel with Bash Array. 2019-03-24. https://unix.stackexchange.com/a/508365/411854
 # Depends: GNU Parallel, GNU Bash v5.1.16, feh 3.6.3
 
@@ -214,6 +214,50 @@ find_flist() {
     if [[ ! -d "$1" ]]; then return 1; fi;
     must find "$1" -maxdepth "$fdepth" -type f -iregex "$firegex" -size +"$fsize";
 }; # print file list to stdout from dir with script parameters
+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)
+    # Depends: yell(), GNU Parallel, GNU find, GNU Coreutils 8.32 (cut, find, du)
+    local list_paths
+    sample_count="100";
+    sample_max_space="100000000"; # bytes
+    
+    if [[ ! -v BKFEH_SAMPLE_DIR ]]; then return 0; fi; # return early if environment var not set.
+    
+    if [[ ! -z "$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="$BKFEH_SAMPLE_DIR";
+        yell "STATUS:Environment variable BKFEH_SAMPLE_DIR set. Clearing and saving samples...";
+        
+        ## clear previous sample
+        count_samples="$(find $BKFEH_SAMPLE_DIR -maxdepth 1 -type f | wc -l)";
+        find "$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 "$list_paths" | shuf | head -n"$sample_count")";
+        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))";
+            if [[ "$sample_req_space" -lt "$sample_max_space" ]]; then
+                #### add file to sample dir
+                cp -n "$line" "$BKFEH_SAMPLE_DIR" ;
+            fi;
+        done < <( echo "$list_paths_sample" );
+    else
+        yell "ERROR:Does not exist: $BKFEH_SAMPLE_DIR";
+    fi;    
+}; # save sample of files
+
 main() {
     # Depends: read_stdin_psarg() v0.0.1, check_depends()
     local re_dotfile;
@@ -226,6 +270,7 @@ main() {
     ## Read stdin as lines
     re_dotfile="^\."; # first char is a dot
     while read -r line; do
+        line="$(readlink -e "$line")";
         # Check if dir
         if [[ ! -d "$line" ]]; then
             echo "ERROR:Not a dir:$line" 1>&2;
@@ -242,6 +287,7 @@ main() {
     ## Read positional arguments as lines
     re_dotfile="^\."; # first char is a dot
     while read -r line; do
+        line="$(readlink -e "$line")";
         # Check if dir
         if [[ ! -d "$line" ]]; then
             echo "ERROR:Not a dir:$line" 1>&2;
@@ -295,6 +341,8 @@ main() {
     # Write
     list_paths_images_tmp="/dev/shm/$(date +%Y%m%dT%H%M%S.%N%z)"..feh_paths.txt;
     must echo -n "$list_paths_images" > "$list_paths_images_tmp";
+    ## Save sample to path in env. var. BKFEH_SAMPLE_DIR if set
+    save_sample "$list_paths_images";
 
     # Print stats
     yell "STATUS:Built file list in $SECONDS seconds.";