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file#

File/dir helpers and download utilities.

Functions#

  • command_exists name

  • Purpose: Return success if a command is available in PATH.

  • directory_exists path

  • file_exists path

  • Purpose: Test for directory/file existence.

  • create_directory path

  • Purpose: Create a directory if missing; prints a message. Returns 0 on success or if it already exists.

  • download_file url [output]

  • Purpose: Download a file using curl or wget.
  • Behavior:
    • If dialog is installed and DOWNLOAD_USE_DIALOG is not false/0/never, automatically uses dialog::dialog_download_file for a progress gauge.
    • Falls back silently to curl or wget with minimal output. curl runs with -f, so an HTTP error (404, 500, ...) is a failure rather than an error page saved as the file.
    • The download goes to a temporary file beside the destination (output.XXXXXX) and is moved into place only on success, with the mode the umask gives a new file. On failure the temporary file is removed: no partial or error-page file is left at the destination, and a file that was already there is left untouched.
  • Returns: 0 on success; the downloader's non-zero status on failure; 1 when neither curl nor wget is installed or the temporary file cannot be created.
  • Args:
    • url - source URL.
    • output - destination path; default derived from URL.

  • Env:

    • DOWNLOAD_USE_DIALOG: auto (default) | true/1 | false/0/never.

  • is_valid_iso file

  • Purpose: Heuristically check if a file is an ISO image (via file).

  • is_valid_checksum file

  • Purpose: Heuristically check if a file looks like an ASCII checksum list.

  • verify_checksum iso_file checksum_file [checksum_type=sha256sum]

  • Purpose: Verify checksum using the specified tool (e.g., sha256sum).
  • Behavior: Finds the entry for iso_file's basename in checksum_file (HASH name, HASH *name, or tagged ALGO (name) = HASH; a listed path matches on its basename), hashes iso_file with checksum_type, and compares (case-insensitive). Other entries in the list do not matter. With shasum, whose default is SHA-1, the algorithm is chosen from the length of the listed digest (40, 56, 64, 96, 128 hex digits: SHA-1, -224, -256, -384, -512), as shasum -c does.

  • Returns: 0 when that entry exists and matches; 1 when it does not match, when the list has no entry for the file, or when the tool is missing; prints success/error.

  • download_iso distro_name

  • Requires bash 4.0 or newer: it reads a DISTROS associative array supplied by the caller, and calls require_bash4 when the shell is older.
  • Purpose: Download ISO based on a DISTROS associative array defined by the caller.
  • Behavior: When the output file already exists, the download is skipped (with a warning) and the existing file is validated; otherwise downloads it. Prints success/error; validates ISO structure.

Dependencies#

  • curl or wget for download, dialog for optional UI, file for validation.