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1 #!/usr/bin/env bash
2
3 # Bash substring parse cheatsheet
4 # -------------------------------
5 # %.* filename.blah.foo.txt -> filename.blah.foo
6 # %%.* filename.blah.foo.txt -> filename
7 # #*. filename.blah.foo.txt -> foo.blah.txt
8 # ##*. filename.blah.foo.txt -> txt
9
10
11
12 # split:
13 # Splits the specified file into the specified number of segments. Output file
14 # is created within the 'out' directory.
15 #
16 # @file Source file to split into multiple segments
17 # @splitcount Number of segments to split @file into.
18 split() {
19 local file="${1}"
20 local splitcount="${2}"
21
22 local lc="$(wc -l ${file} | cut -d ' ' -f 1)"
23 local lps=$(( lc / splitcount + 1 )) # Calculate lines per segment
24 local segment=0 # Current file segment int
25 local segline=0 # Current line in the current segment
26 local outfile='' # Current output file segment path
27
28 # Filename without extension (filename.txt -> filename)
29 local filebase="${file%.*}"
30 # File extension (filename.txt -> txt)
31 local fileext=".${file##*.}"
32
33 # If file extension is the same as the file base (with a preceeding dot), the
34 # source file has no extention. Set this variable to empty so the extention
35 # will be the segment number
36 [ "${fileext}" = ".${filebase}" ] && fileext=''
37
38 # Create output directory to keep things a bit more organized
39 [ ! -d out ] && mkdir out
40
41 # Ensure IFS is only separating on newlines
42 local oldifs="${IFS}"
43 export IFS=$'\n'
44
45
46 # Update the outfile path
47 outfile="out/${filebase}.${segment}${fileext}"
48 # Truncate the current output segment file. If we skip this and the file
49 # already exists, we will append to an existing file, corrupting output.
50 > "${outfile}"
51 printf "Writing to '%s' segment\n" "${outfile}"
52
53
54 # Iterrate over the source file, line by line.
55 for line in $(cat ${file}); do
56 if [ "${segline}" -eq "${lps}" ]; then
57 # Increment the file segment counter
58 segment=$(( segment + 1 ))
59 # Reset the segment line counter
60 segline=0
61
62 # Update the outfile path
63 outfile="out/${filebase}.${segment}${fileext}"
64 > "${outfile}"
65 printf "Writing to '%s' segment\n" "${outfile}"
66 fi
67
68 # Append line to segment file
69 printf -- "%s\n" "${line}" >> "${outfile}"
70
71 # Increment the segment line counter so we can ensure we don't write past
72 # the 'lines per segement' (lps) var.
73 segline=$(( segline + 1 ))
74 done
75
76 export IFS="${oldifs}"
77 }
78
79
80 main() {
81 local file="${1}"
82 local count="${2}"
83
84 # Ensure file and segment count are specified
85 [ -z "${file}" ] && printf "Filename required\n" && return 1
86 [ -z "${count}" ] && printf "Segment count required\n" && return 1
87
88 # Split (Croatia)!
89 split "${file}" "${count}"
90 }
91
92 main ${@}
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