1. rcrnstn/dotd
  2. Commit 14afd48f3876e48b65ed61cbfccf989920ab5cb7
Browse code

Add argument parsing

Robert Cranston authored on 28/11/2021 17:08:00
Showing 2 changed files
  • README.md index ec865b0..97b9c83 100644
  • dotd index 0000000..6ed9b3b
README.md
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@@ -11,6 +11,66 @@ functionality equivalent to `include config.d/*`. In essence, it is a glorified
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 [`dotd`]: https://git.rcrnstn.net/rcrnstn/dotd
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+## Usage
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+
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+`dotd --help`:
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+
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+```
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+dotd 1.0
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+
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+Generate a file from fragment files in a directory.
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+
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+usage:
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+  dotd [options] [--] <file> [<dir>]
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+  dotd -h|--help
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+  dotd --version
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+
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+arguments:
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+  <file>
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+    File to generate. Specify - to print to stdout instead.
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+
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+  <dir>
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+    Directory containing fragment files. <file>.d is used if not
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+    specified.
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+
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+options:
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+  -a, --action <action>
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+    Action to perform on each fragment file. E.g.
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+      printf "#include \"%s\"\n"
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+    [default: cat]
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+
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+  -c, --comment <comment>
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+    If non-empty, adds comments starting with <comment> that the file is
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+    auto-generated and which fragment corresponds to which file.
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+    [default: ]
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+
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+  -g, --glob <glob>
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+    Shell glob used to find fragment files, relative to <dir>.
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+    [default: *]
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+
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+  -v, --validate <validate>
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+    Command to run on the (temporary) generated file. Only if the command
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+    returns success is the file moved to its final destination. E.g.
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+      /usr/sbin/sshd -t -f
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+    [default: ]
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+```
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+
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+## Dependencies
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+
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+All dependencies are [POSIX][] and are highly likely to be installed by default
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+(e.g. they all have the [Debian priority][] `required`).
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+
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+-   `sh` (e.g. from [`bash`][] or [`dash`][])
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+-   `sed` (e.g. from [`sed`][])
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+-   `awk` (e.g. from [`mawk`][])
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+
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+[POSIX]: https://en.wikipedia.org/wiki/POSIX
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+[Debian priority]: https://www.debian.org/doc/debian-policy/ch-archive.html#s-priorities
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+[`bash`]: https://packages.debian.org/bash
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+[`dash`]: https://packages.debian.org/dash
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+[`sed`]: https://packages.debian.org/sed
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+[`mawk`]: https://packages.debian.org/mawk
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+
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 ## Related projects
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 -   [Ansible][]'s [`assemble` module][].
dotd
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@@ -0,0 +1,86 @@
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+#!/bin/sh
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+set -euC
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+
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+##/// dotd 1.0
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+#////
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+#//// Generate a file from fragment files in a directory.
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+#////
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+###// usage:
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+#////   dotd [options] [--] <file> [<dir>]
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+#////   dotd -h|--help
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+#////   dotd --version
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+#////
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+###// arguments:
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+####/   <file>
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+#////     File to generate. Specify - to print to stdout instead.
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+#////
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+####/   <dir>
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+#////     Directory containing fragment files. <file>.d is used if not
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+#////     specified.
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+#////
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+###// options:
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+####/   -a, --action <action>
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+#////     Action to perform on each fragment file. E.g.
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+#////       printf "#include \"%s\"\n"
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+#////     [default: cat]
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+#////
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+####/   -c, --comment <comment>
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+#////     If non-empty, adds comments starting with <comment> that the file is
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+#////     auto-generated and which fragment corresponds to which file.
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+#////     [default: ]
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+#////
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+####/   -g, --glob <glob>
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+#////     Shell glob used to find fragment files, relative to <dir>.
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+#////     [default: *]
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+#////
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+####/   -v, --validate <validate>
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+#////     Command to run on the (temporary) generated file. Only if the command
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+#////     returns success is the file moved to its final destination. E.g.
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+#////       /usr/sbin/sshd -t -f
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+#////     [default: ]
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+
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+## Messages
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+help()    { sed -n 's|^#[#/]*/ \?||p' "$0";              exit 0;    }
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+version() { help | awk '/^$/{++p;next}p==0';             exit 0;    }
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+usage()   { help | awk '/^$/{++p;next}p==2';             exit 0;    }
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+parse()   { printf '%s: error: %s\n'   "$0" "$1"; usage; exit 1;    } >&2
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+error()   { printf '%s: error: %s\n'   "$0" "$1";        exit 1;    } >&2
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+warning() { printf '%s: warning: %s\n' "$0" "$1";                   } >&2
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+opt()     { [ $# -gt 1 ] || parse "option '$1' value not provided"; }
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+arg()     { [ $# -gt 1 ] || parse "argument '$1' not provided";     }
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+
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+## Parse special options
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+case "${1-}"
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+in
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+  '-h'|'--help') help; ;;
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+  '--version') version; ;;
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+esac
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+
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+## Parse options
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+action='cat'
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+comment=''
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+glob='*'
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+validate=''
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+while [ $# -gt 0 ]
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+do
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+  case "$1"
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+  in
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+    '-a'|'--action')   shift; opt 'action'   "$@"; action="$1";   ;;
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+    '-c'|'--comment')  shift; opt 'comment'  "$@"; comment="$1";  ;;
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+    '-g'|'--glob')     shift; opt 'glob'     "$@"; glob="$1";     ;;
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+    '-v'|'--validate') shift; opt 'validate' "$@"; validate="$1"; ;;
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+    '--') shift; break; ;;
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+    '-'?*) parse "unrecognized option '$1'"; ;;
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+    *) break; ;;
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+  esac
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+  shift
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+done
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+
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+## Parse required arguments
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+arg 'file' "$@"; file="$1"; shift;
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+
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+## Parse optional arguments
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+dir="${1-}"; shift $(($#>0));
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+
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+## Parse unrecognized arguments
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+[ $# -eq 0 ] || parse "unrecognized argument: '$1'"