I have to download a file from this link. The file download is a zip file which I will have to unzip in the current folder.

Normally, I would download it first, then run the unzip command.

$ wget http://www.vim.org/scripts/download_script.php?src_id=11834 -O temp.zip
$ unzip temp.zip

But in this way, I need to execute two commands, wait for the completion of first one to execute the next one, also, I must know the name of the file temp.zip to give it to unzip.

Is it possible to redirect output of wget to unzip? Something like

$ unzip < `wget http://www.vim.org/scripts/download_script.php?src_id=11834`

But it didn't work.

bash: wget http://www.vim.org/scripts/download_script.php?src_id=11834 -O temp.zip: ambiguous redirect

Also, wget got executed twice, and downloaded the file twice.

  • In the latter example, wget probably was executed twice because the ? is a special character in the shell. Putting the URL in ""s should help. – p-static Oct 8 '10 at 0:32
  • This thread seems to have a solution. Haven't tried it myself though. serverfault.com/questions/26474/… – user37850 Apr 25 '13 at 13:00
up vote 78 down vote accepted

You have to download your files to a temp file, because (quoting the unzip man page):

Archives read from standard input are not yet supported, except with funzip (and then only the first member of the archive can be extracted).

Just bring the commands together:

wget http://www.vim.org/scripts/download_script.php?src_id=11834 -O temp.zip; unzip temp.zip; rm temp.zip

But in order to make it more flexible you should probably put it into a script so you save some typing and in order to make sure you don't accidentally overwrite something you could use the mktemp command to create a safe filename for your temp file:

#!/bin/bash
TMPFILE=`mktemp`
PWD=`pwd`
wget "$1" -O $TMPFILE
unzip -d $PWD $TMPFILE
rm $TMPFILE
  • Is wget file.zip && unzip file.zip the same as wget file.zip; unzip file.zip or is one preferred over the other? Thanks :) – jaggedsoft Dec 3 '16 at 20:10
  • 6
    @NextLocal wget && unzip will run unzip only if wget succeeded. wget ; unzip will run unzip anyway, possibly pointing to non existent file. – temoto Feb 7 '17 at 11:37

This is a repost of my answer to a similar question:

The ZIP file format includes a directory (index) at the end of the archive. This directory says where, within the archive each file is located and thus allows for quick, random access, without reading the entire archive.

This would appear to pose a problem when attempting to read a ZIP archive through a pipe, in that the index is not accessed until the very end and so individual members cannot be correctly extracted until after the file has been entirely read and is no longer available. As such it appears unsurprising that most ZIP decompressors simply fail when the archive is supplied through a pipe.

The directory at the end of the archive is not the only location where file meta information is stored in the archive. In addition, individual entries also include this information in a local file header, for redundancy purposes.

Although not every ZIP decompressor will use local file headers when the index is unavailable, the tar and cpio front ends to libarchive (a.k.a. bsdtar and bsdcpio) can and will do so when reading through a pipe, meaning that the following is possible:

wget -qO- http://example.org/file.zip | bsdtar -xvf-
  • 1
    This is excellent! I would note that tar gives me some warnings about the uncompressed data being the wrong size (expected 0), but the files themselves appear to be undamaged. Guessing this is due to the lack of the index. – Wyatt8740 Mar 17 at 7:50
  • 1
    I have a .zip-file here that contains files with executable permissions. When I download and pipe into bsdtar, the exec bits get thrown away. When I download to disk and extract with bsdtar or unzip then, the exec bits are honoured. – Golar Ramblar May 4 at 16:02
  • // , @GolarRamblar, didst ever find out why? – Nathan Basanese Sep 27 at 19:16
  • @NathanBasanese: I did not dig deeper into it. – Golar Ramblar yesterday

If you have the JDK installed, you can use jar:

wget -qO- http://example.org/file.zip | jar xvf /dev/stdin
  • 3
    I just found that jar doesn't preserve file permissions. Nice trick otherwise. – phunehehe Dec 25 '16 at 10:15
  • 4
    You don't need to give a file param, just use | jar xv – cricket_007 Aug 25 '17 at 15:55

I don't think you even want to bother piping wget's output into unzip.

From the wikipedia "ZIP (file format)" article:

A ZIP file is identified by the presence of a central directory located at the end of the file.

wget has to completely finish the download before unzip can do any work, so they run sequentially, not interwoven as one might think.

The proper syntax would be:

$ unzip <(curl -sL https://www.winpcap.org/archive/1.0-docs.zip)

but it won't work, because of the error (Info-ZIP on Debian):

lseek(3, 0, SEEK_SET)                   = -1 ESPIPE (Illegal seek)

Archive:  /dev/fd/63
  End-of-central-directory signature not found.  Either this file is not
  a zipfile, or it constitutes one disk of a multi-part archive.  In the
  latter case the central directory and zipfile comment will be found on
  the last disk(s) of this archive.
unzip:  cannot find zipfile directory in one of /dev/fd/63 or
        /dev/fd/63.zip, and cannot find /dev/fd/63.ZIP, period.

or on BSD/OS X:

Trying to read large file (> 2 GiB) without large file support

This is, because the standard zip tools are mainly using lseek function in order to set the file offset at the end to read its end of central directory record. It is located at the end of the archive structure and it is required to read the list of the files (see: Zip file format structure). Therefore the file cannot be FIFO, pipe, terminal device or any other dynamic, because the input object cannot be positioned by the lseek function.

So you have the following workarounds:

  • use different kind of compression (e.g. tar.gz),
  • you have to use two separate commands,
  • use alternative tools (as suggested in other answers),
  • create an alias or function to use multiple commands.
  • I think it still could be a FIFO. You'd just have to keep reading from the FIFO until EOF (effectively buffering the whole FIFO in memory or in a temp file). Totally doable to ease script creation, but not very useful. – Evan Carroll Oct 9 '16 at 20:28

Repost of my answer:

BusyBox's unzip can take stdin and extract all the files.

wget -qO- http://downloads.wordpress.org/plugin/akismet.2.5.3.zip | busybox unzip -

The dash after unzip is to use stdin as input.

You can even,

cat file.zip | busybox unzip -

But that's just redundant of unzip file.zip.

If your distro uses BusyBox by default (e.g. Alpine), just run unzip -.

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