Initial commitHEADmaster

This includes the readme, license, and the bash implementation of the
file segmenter.

4 files changed, 144 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
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+out
diff --git a/LICENSE b/LICENSE
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+Copyright 2018 Aaron Ball <nullspoon@oper.io>
+
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its contributors
+   may be used to endorse or promote products derived from this software without
+   specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/README.adoc b/README.adoc
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+README
+======
+
+Various implementations of a file segmenter. Note that all of these preserve
+the original file after segmentation.
+
+
+file-segment.sh
+---------------
+
+Bash implementation. Takes two arguments: **filename** and **segment count**.
+
+Usage
+~~~~~
+
+  file-segment.sh <filename.txt> <segment_count>
+
+
+Example
+~~~~~~~
+
+  file-segment.sh /var/log/messages 8
+
+This example will create an **out** directory containing 8 segments of the file
+/var/log/messages.
diff --git a/segment-file.sh b/segment-file.sh
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+#!/usr/bin/env bash
+
+# Bash substring parse cheatsheet
+# -------------------------------
+#   %.*  filename.blah.foo.txt -> filename.blah.foo
+#   %%.* filename.blah.foo.txt -> filename
+#   #*.  filename.blah.foo.txt -> foo.blah.txt
+#   ##*. filename.blah.foo.txt -> txt
+
+
+
+# split:
+# Splits the specified file into the specified number of segments. Output file
+# is created within the 'out' directory.
+#
+# @file         Source file to split into multiple segments
+# @splitcount   Number of segments to split @file into.
+split() {
+  local file="${1}"
+  local splitcount="${2}"
+
+  local lc="$(wc -l ${file} | cut -d ' ' -f 1)"
+  local lps=$(( lc / splitcount + 1 ))  # Calculate lines per segment
+  local segment=0                   # Current file segment int
+  local segline=0                   # Current line in the current segment
+  local outfile=''                  # Current output file segment path
+
+  # Filename without extension (filename.txt -> filename)
+  local filebase="${file%.*}"
+  # File extension (filename.txt -> txt)
+  local fileext=".${file##*.}"
+
+  # If file extension is the same as the file base (with a preceeding dot), the
+  # source file has no extention. Set this variable to empty so the extention
+  # will be the segment number
+  [ "${fileext}" = ".${filebase}" ] && fileext=''
+
+  # Create output directory to keep things a bit more organized
+  [ ! -d out ] && mkdir out
+
+  # Ensure IFS is only separating on newlines
+  local oldifs="${IFS}"
+  export IFS=$'\n'
+
+
+  # Update the outfile path
+  outfile="out/${filebase}.${segment}${fileext}"
+  # Truncate the current output segment file. If we skip this and the file
+  # already exists, we will append to an existing file, corrupting output.
+  > "${outfile}"
+  printf "Writing to '%s' segment\n" "${outfile}"
+
+
+  # Iterrate over the source file, line by line.
+  for line in $(cat ${file}); do
+    if [ "${segline}" -eq "${lps}" ]; then
+      # Increment the file segment counter
+      segment=$(( segment + 1 ))
+      # Reset the segment line counter
+      segline=0
+
+      # Update the outfile path
+      outfile="out/${filebase}.${segment}${fileext}"
+      > "${outfile}"
+      printf "Writing to '%s' segment\n" "${outfile}"
+    fi
+
+    # Append line to segment file
+    printf -- "%s\n" "${line}" >> "${outfile}"
+
+    # Increment the segment line counter so we can ensure we don't write past
+    # the 'lines per segement' (lps) var.
+    segline=$(( segline + 1 ))
+  done
+
+  export IFS="${oldifs}"
+}
+
+
+main() {
+  local file="${1}"
+  local count="${2}"
+
+  # Ensure file and segment count are specified
+  [ -z "${file}" ] && printf "Filename required\n" && return 1
+  [ -z "${count}" ] && printf "Segment count required\n" && return 1
+
+  # Split (Croatia)!
+  split "${file}" "${count}"
+}
+
+main ${@}