hashDownload: Download and store hash value from downloaded file

In PredictiveEcology/webDatabases: Find And Download Canadian Forestry, Ecological And Other Natural Places Data

Description

To avoid redownloading existing files, verify if the file exists locally. If the file exists, compare the checksum value to that logged by original download.

Usage

hashDownload(urls, destfile, checkhash = TRUE, quick = FALSE,
  dbHash = getOption("webdatabases.dbfile"), cascade = FALSE,
  quiet = TRUE)

Arguments

urls	A character string. Represents the url of file to be downloaded.
destfile	A character string. Represents the name where resulting file is saved.
checkhash	Logical. If TRUE (default), check if file exists locally and cross-check the file's checksum value with that logged from a previous event, skippng redownload if checksum matches. When checksums don't match or file doesn't exist locally, the file is downloaded and its checksum computed. If FALSE, the function is executed even if the file is found locally.
quick	Logical. If TRUE, checksum is compiled using the combination of the filename and its size. If FALSE (default), cheksum is compiled using the object.
dbHash	Character string. The path to the database file where checksum value of file is logged. If the database does not yet exist, one is created. Default is to use the option webdatabases.dbfile.
cascade	Logical. If FALSE, file is untar and/or unzip. Default is FALSE.
quiet	Logical. If TRUE, suppress status messages (if any), and the progress bar.

Value

Invoked for its side-effect of downloading files to the destfile/ directory.

Author(s)

Melina Houle

Examples

## Not run: 
u <-"http://ftp.geogratis.gc.ca/pub/nrcan_rncan/archive/vector/cli_itc_50k/land_use/L040J03.zip"
hashDownload(urls = u, destfile = tempdir(), checkhash = FALSE, cascade = FALSE)

## End(Not run)

PredictiveEcology/webDatabases documentation built on May 8, 2019, 3:09 p.m.