Commit | Line | Data |
---|---|---|
8942e536 SBS |
1 | #!/usr/bin/env bash |
2 | # Desc: Adds blank line every 4 lines | |
3 | # Usage: cat file | space4 | |
4 | # Example: seq 1 10 | space 4 | |
5 | # Version: 0.0.1 | |
6 | # Depends: Bash 5.1.16 | |
7 | ||
8 | yell() { echo "$0: $*" >&2; } # print script path and all args to stderr | |
9 | die() { yell "$*"; exit 111; } # same as yell() but non-zero exit status | |
10 | must() { "$@" || die "cannot $*"; } # runs args as command, reports args if command fails | |
11 | read_stdin() { | |
12 | # Desc: Consumes stdin; outputs as stdout lines | |
13 | # Input: stdin (consumes) | |
14 | # Output: stdout (newline delimited) | |
15 | # Example: printf "foo\nbar\n" | read_stdin | |
16 | # Depends: GNU bash (version 5.1.16) | |
17 | # Version: 0.0.1 | |
18 | local input_stdin output; | |
19 | ||
20 | # Store stdin | |
21 | if [[ -p /dev/stdin ]]; then | |
22 | input_stdin="$(cat -)"; | |
23 | fi; | |
24 | ||
25 | # Store as output array elements | |
26 | ## Read in stdin | |
27 | if [[ -n $input_stdin ]]; then | |
28 | while read -r line; do | |
29 | output+=("$line"); | |
30 | done < <(printf "%s\n" "$input_stdin"); | |
31 | fi; | |
32 | ||
33 | # Print to stdout | |
34 | printf "%s\n" "${output[@]}"; | |
35 | }; # read stdin to stdout lines | |
36 | main() { | |
37 | # Depends: BK-2020-03: yell(), die(), must(), read_stdin() | |
38 | if [[ $# -gt 0 ]]; then die "FATAL:This script uses no positional arguments.:$#"; fi; | |
39 | n=0; | |
40 | while read -r line; do | |
41 | printf "%s\n" "$line"; | |
42 | if ! (( (n + 1) % 4 )); then | |
43 | printf "\n"; | |
44 | fi; | |
45 | ((n++)); | |
46 | done < <(read_stdin); | |
47 | }; # main program | |
48 | ||
49 | main "$@"; | |
50 | ||
51 | # Author: Steven Baltakatei Sandoval | |
52 | # License: GPLv3+ |