feat(user/bkots):Use subshells to speed up jobs

[BK-2020-03.git] / user / zeropad.sh

diff --git a/user/zeropad.sh b/user/zeropad.sh
index e8b2a88715d6b52ebe0ad0fe0b360a273c7a01c0..242b30be2e8399d3175f5bced308494b9c184378 100755 (executable)
--- a/user/zeropad.sh
+++ b/user/zeropad.sh
@@ -1,24 +1,78 @@
 #!/bin/bash
 # Desc: Zero-pad working dir files with initial digits for sorting
-# Usage: zeropad.sh
-# Version: 0.0.2
+# Usage: zeropad.sh [str fext]
+# Example: zeropad.sh;
+#          zeropad.sh ".jpg";
+# Input: arg1  str  file extension of files to apply changes to
+# Version: 0.2.0
 
-# Find the maximum number of leading digits in the filenames of working dir
-max_digits="$(ls -1 * | sed 's/[^0-9].*//' | awk '{ if(length > L) L=length } END { print L }')";
-declare -p max_digits;
+declare fext; # file extension
 
-# Loop over the files and rename them
-for file in *; do
-  # Extract the leading digits
-  digits="$(echo "$file" | sed 's/\([0-9]*\).*/\1/')";
-  # Zero-pad the digits
-  padded_digits="$(printf "%0${max_digits}d" "$digits")";
-  # Construct the new filename
-  new_file="${padded_digits}${file#${digits}}";
-  # Rename the file
-  mv -n "$file" "$new_file"
-  # declare -p file new_file; # debug
-done;
+list_files() {
+    # Desc: Lists working directory file basenames
+    # Usage: list_files
+    # Input: fext  var  file extension
+    # Output: stdout  a line-delimited list of file names
+    if [[ -z "$fext" ]]; then
+        find . -mindepth 1 -maxdepth 1 -type f -exec basename '{}' \; ;
+    else
+        find . -mindepth 1 -maxdepth 1 -type f -exec basename '{}' \; \
+            | grep -E -- "${fext}$" ;
+    fi;
+}; # list pwd file basenames
+remove_leading_zeroes() {
+    # Desc: Removes leading zeroes from lines
+    # Input: stdin
+    # Output: stdout
+    # Depends: BK-2020-03 read_stdin()
+    # Version: 0.0.1
+    while read -r line; do
+        printf "%s\n" "$line" | sed -E -e 's/(^0*)([0-9].*)/\2/';
+    done;
+};
+get_max_digits() {
+    # Desc: Returns max leading digits of pwd filenames
+    # Depends: list_files()
+    #          BK-2020-03:  remove_leading_zeroes()
+    #          GNU sed 4.8
+    #          GNU awk 5.1.0
+    local output;
+    
+    # Find the maximum number of leading digits in the filenames of working dir
+    output="$(list_files | remove_leading_zeroes \
+        | awk '{ match($0, /^[0-9]+/); if (RLENGTH > max) max=RLENGTH } END { print max }' )";
+    # declare -p max_digits; # debug
+    printf "%s" "$output";
+}; # return max digits to stdout
+main () {
+    # Read file extension if provided
+    if [[ -n "$1" ]]; then
+        fext="$1";
+    fi;
+
+    max_digits="$(get_max_digits)";
+
+    # Loop over the files and rename them
+    while read -r file; do
+        # Skip files with no leading digits
+        re='^[0-9]+';
+        if [[ ! "$file" =~ $re ]]; then continue; fi;
+
+        # Extract the leading digits
+        digits="$(echo "$file" | sed -E 's/([0-9]*).*/\1/')"; # all leading digits
+        digits_nlz="$(echo "$digits" | remove_leading_zeroes)"; # no leading zeroes
+        # Zero-pad the digits
+        padded_digits="$(printf "%0${max_digits}d" "$digits_nlz")";
+        # Construct the new filename
+        new_file="${padded_digits}${file#${digits}}";
+        # Rename the file
+        if [[ "$file" == "$new_file" ]]; then continue; fi;
+        mv -n "$file" "$new_file";
+        #declare -p max_digits file digits digits_nlz padded_digits new_file # debug
+    done < <(list_files);
+}; # main program
+
+main "$@";
 
 # Author: Steven Baltakatei Sandoval
 # License: GPLv3+