如果您在系统上安装了
lftp
工具,则可以使用其
find
命令递归列出指定目录下的文件。这里是一个指向文档的
链接,
find
的描述在顶部附近。
不幸的是,正如您从文档中看到的那样,与普通的 Unix
find
工具不同,
lftp
的
find
命令几乎不支持任何选项,只有
--max-depth
和
--list
(用于长列表),因此您无法使用
-name
、
-regex
等谓词,这些谓词通常由
find
工具提供。另一方面,
lftp
支持一种非常不寻常但强大的功能,即允许您将输出管道传输到本地工具,因此您可以从
lftp
命令行内部将
find
输出管道传输到本地的
grep
。当然,您也可以在 shell 管道中进行 grep 或在 Rland 中进行过滤。以下是使用
lftp
管道的示例(正如您所看到的,这种方法的缺点是多层转义变得相当复杂):
url <- 'ftp://ftp-cdc.dwd.de/pub/CDC/observations_germany/climate/hourly/';
zips <- system(paste0('lftp ',url,' <<<\'find| grep "\\\\.zip$"; exit;\';'),intern=T);
zips;
## [1] "./air_temperature/historical/stundenwerte_TU_00003_19500401_20110331_hist.zip"
## [2] "./air_temperature/historical/stundenwerte_TU_00044_20070401_20141231_hist.zip"
## [3] "./air_temperature/historical/stundenwerte_TU_00052_19760101_19880101_hist.zip"
## [4] "./air_temperature/historical/stundenwerte_TU_00071_20091201_20141231_hist.zip"
##
## ... snip ...
##
## [6616] "./wind/recent/stundenwerte_FF_15207_akt.zip"
## [6617] "./wind/recent/stundenwerte_FF_15214_akt.zip"
## [6618] "./wind/recent/stundenwerte_FF_15444_akt.zip"
## [6619] "./wind/recent/stundenwerte_FF_15520_akt.zip"
另外,只是为了好玩,如果你想要另一种方法,我已经写了一个函数,可以使用正则表达式解析ls -l
命令的输出,将所有字段返回到数据框中。简单的修改允许它使用lftp
在ftp上工作:
longListing <- function(url='',recursive=F,all=F) {
url <- as.character(url);
if (length(url) != 1L) stop('url argument must have length 1.');
recursive <- as.logical(recursive);
if (length(recursive) != 1L) stop('recursive argument must have length 1.');
all <- as.logical(all);
if (length(all) != 1L) stop('all argument must have length 1.');
urlEsc <- if (url == '') '' else paste0('\'',sub("'","'\\''",url),'\'');
lsCmd <- paste0('ls -l',if (recursive) ' -R',if (all) ' -A');
if (substr(url,0L,6L) == 'ftp://') {
output <- system(paste0('lftp ',urlEsc,' <<<\'',lsCmd,'; exit;\';'),intern=T);
} else {
output <- system(paste0(lsCmd,' ',urlEsc,';'),intern=T);
};
sp0RE <- '\\s*';
sp1RE <- '\\s+';
typeRE <- '([?dlcbps-])';
rRE <- '([?r-])';
wRE <- '([?w-])';
xRE <- '([?xsStT-])';
aclRE <- '([?+@]*)';
permRE <- paste0(typeRE,rRE,wRE,xRE,rRE,wRE,xRE,rRE,wRE,xRE,aclRE);
linksRE <- '(\\?|[0-9]+)';
ocRE <- '[a-zA-Z_0-9.$+-]';
ocsRE <- '[a-zA-Z_0-9 .$+-]';
ownerRE <- paste0('(\\?|',ocRE,'|',ocRE,ocsRE,'*?',ocRE,')');
groupRE <- ownerRE;
sizeRE <- '(?:\\?|(?:([0-9]+),\\s*)?([0-9]+))';
monthRE <- '(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)';
dayRE <- '([0-9]+)';
timeRE <- '([0-9]{2}:[0-9]{2}|[0-9]+)';
dtRE <- paste0('(?:\\?|',monthRE,sp1RE,dayRE,sp1RE,timeRE,')');
nameRE <- '(.*?)';
targetRE <- '(?:\\s+->\\s+(.*))?';
recordRE <- paste0(
'^'
,permRE,sp1RE
,linksRE,sp1RE
,ownerRE,sp1RE
,groupRE,sp1RE
,sizeRE,sp1RE
,dtRE,sp1RE
,nameRE,targetRE
,sp0RE,'$'
);
recordIndexes <- grep(recordRE,output);
blankIndexes <- grep('^\\s*$',output);
headerIndexes <- grep(':$',output);
headerIndexes <- headerIndexes[(headerIndexes-1)%in%c(0L,blankIndexes)];
recordHeaderIndexes <- findInterval(recordIndexes,headerIndexes);
parentPaths <- c('',sub(':','/',output[headerIndexes]))[recordHeaderIndexes+1L];
parentPaths <- sub('^\\./','',parentPaths);
reg <- regmatches(output[recordIndexes],regexec(recordRE,output[recordIndexes]));
ret <- data.frame(type=sapply(reg,`[`,2L),stringsAsFactors=F);
i <- 3L;
for (cn in c('ur','uw','ux','gr','gw','gx','or','ow','ox','acl','links','owner','group','major','size','month','day','time','path','target')) {
ret[[cn]] <- sapply(reg,`[`,i);
i <- i+1L;
};
ret$path <- paste0(parentPaths,ret$path);
ret;
};
这是我在系统上创建的一个特殊文件目录的演示:
longListing();
## type ur uw ux gr gw gx or ow ox acl links owner group major size month day time path target
## 1 d r w x r - - r - - + 1 user None 0 Feb 27 08:21 dir
## 2 d r w x r w x r w x + 1 user None 0 Feb 27 08:21 dir-other-writable
## 3 d r w x r - - r - T + 1 user None 0 Feb 27 08:21 dir-sticky
## 4 d r w x r w x r w t + 1 user None 0 Feb 27 08:21 dir-sticky-other-writable
## 5 - r w - r - - r - - 2 user None 0 Feb 27 08:21 file
## 6 - r w - r - - r - - 1 user None 0 Feb 27 08:21 file-archive.tar
## 7 - r w - r - - r - - 1 user None 0 Feb 27 08:21 file-audio.mp3
## 8 b r w - r w - r w - 1 user None 0 1 Feb 27 08:21 file-block-special
## 9 c r w - r w - r w - 1 user None 0 1 Feb 27 08:21 file-character-special
## 10 - r w x r w x r w x 1 user None 12 Feb 27 08:21 file-exe
## 11 p r w - r w - r w - 1 user None 0 Feb 27 08:21 file-fifo
## 12 - r w - r - - r - - 1 user None 0 Feb 27 08:21 file-image.bmp
## 13 - r w - r w S r - - 1 user None 0 Feb 27 08:21 file-setgid
## 14 - r w x r w s r - x 1 user None 0 Feb 27 08:21 file-setgid-exe
## 15 - r w S r w - r - - 1 user None 0 Feb 27 08:21 file-setuid
## 16 - r w s r w x r - x 1 user None 0 Feb 27 08:21 file-setuid-exe
## 17 s r w - r w - r - - 1 user None 0 Feb 27 08:21 file-socket
## 18 l r w x r w x r w x 1 user None 4 Feb 27 08:21 ln-existing file
## 19 - r w - r - - r - - 2 user None 0 Feb 27 08:21 ln-hard
## 20 l r w x r w x r w x 1 user None 17 Feb 27 08:21 ln-non-existing file-non-existing
在您的网站上演示:
url <- 'ftp://ftp-cdc.dwd.de/pub/CDC/observations_germany/climate/hourly/';
ll <- longListing(url,T,T);
ll;
## type ur uw ux gr gw gx or ow ox acl links owner group major size month day time path target
## 1 d r w x r w x - - x 4 32230 ftp-dwd 4096 Jun 5 2014 air_temperature
## 2 d r w x r w x - - x 4 32230 ftp-dwd 4096 Sep 25 2014 cloudiness
## 3 d r w x r w x - - x 4 32230 ftp-dwd 4096 Nov 13 2014 precipitation
## 4 d r w x r w x - - x 4 32230 ftp-dwd 4096 Nov 13 2014 pressure
## 5 d r w x r w x - - x 4 32230 ftp-dwd 4096 Jun 5 2014 soil_temperature
## 6 d r w x r w x - - x 2 32230 ftp-dwd 12288 Dec 15 11:52 solar
## 7 d r w x r w x - - x 4 32230 ftp-dwd 4096 Jun 5 2014 sun
## 8 d r w x r w x - - x 4 32230 ftp-dwd 4096 Apr 17 2015 wind
## 9 d r w x r w x - - x 2 32230 ftp-dwd 114688 Oct 15 12:35 air_temperature/historical
## 10 d r w x r w x - - x 2 32230 ftp-dwd 151552 Dec 4 10:28 air_temperature/recent
## 11 - r w - r w - - - - 1 32230 ftp-dwd 68727 Jan 26 09:55 air_temperature/historical/BESCHREIBUNG_obsgermany_climate_hourly_tu_historical_de.pdf
## 12 - r w - r w - - - - 1 32230 ftp-dwd 68600 Jan 26 09:55 air_temperature/historical/DESCRIPTION_obsgermany_climate_hourly_tu_historical_en.pdf
## 13 - r w - r w - - - - 1 32230 ftp-dwd 123634 Mar 27 2015 air_temperature/historical/TU_Stundenwerte_Beschreibung_Stationen.txt
## 14 - r w - r w - - - - 1 32230 ftp-dwd 2847045 Mar 27 2015 air_temperature/historical/stundenwerte_TU_00003_19500401_20110331_hist.zip
## 15 - r w - r w - - - - 1 32230 ftp-dwd 359517 Mar 27 2015 air_temperature/historical/stundenwerte_TU_00044_20070401_20141231_hist.zip
##
## ... snip ...
##
## 6683 - r w - r w - - - - 1 32230 ftp-dwd 65633 Feb 27 10:26 wind/recent/stundenwerte_FF_15207_akt.zip
## 6684 - r w - r w - - - - 1 32230 ftp-dwd 66910 Feb 27 10:21 wind/recent/stundenwerte_FF_15214_akt.zip
## 6685 - r w - r w - - - - 1 32230 ftp-dwd 64525 Feb 27 10:19 wind/recent/stundenwerte_FF_15444_akt.zip
## 6686 - r w - r w - - - - 1 32230 ftp-dwd 23717 Feb 27 10:21 wind/recent/stundenwerte_FF_15520_akt.zip
您可以轻松提取zip文件名:
zips <- ll$path[ll$type=='-' & grepl('\\.zip$',ll$path)]
length(zips)
rdwd
包可能会有所帮助:https://github.com/brry/rdwd#rdwd。它包括一个观测气候数据的文件索引,一个递归列出 FTP 目录的功能 (indexDWD
),以及一个天气站互动地图。 - Berry Boessenkool