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Accepted
Bo Jeanes
Asked: 2010-01-07 21:39:26 +0800 CST

Updating a file in a zip archive from STDIN

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I want to update/freshen a file in a zip archive with the contents of stdin. So far I haven't been able to find a way to tell the zip command that the contents of stdin correspond to a particular file.

E.g. (the last line is how I'd expect it to work but it doesn't make any changes to the zip file):

~/D/tmp ♪ unzip -l sample.odt # an odt file is actually a zip file
Archive:  sample.odt
  Length     Date   Time    Name
 --------    ----   ----    ----
       39  01-06-10 00:46   mimetype
        0  01-06-10 00:46   Configurations2/statusbar/
        0  01-06-10 00:46   Configurations2/accelerator/current.xml
        0  01-06-10 00:46   Configurations2/floater/
        0  01-06-10 00:46   Configurations2/popupmenu/
        0  01-06-10 00:46   Configurations2/progressbar/
        0  01-06-10 00:46   Configurations2/menubar/
        0  01-06-10 00:46   Configurations2/toolbar/
        0  01-06-10 00:46   Configurations2/images/Bitmaps/
     3374  01-06-10 00:46   content.xml
    11837  01-06-10 00:46   styles.xml
      957  01-06-10 00:46   meta.xml
     1060  01-06-10 00:46   Thumbnails/thumbnail.png
     8086  01-06-10 00:46   settings.xml
     1889  01-06-10 00:46   META-INF/manifest.xml
 --------                   -------
    27242                   15 files
~/D/tmp ♪ unzip -p sample.odt meta.xml > tmp.xml
~/D/tmp ♪ # modify tmp.xml somehow
~/D/tmp ♪ cat tmp.xml | zip sample.odt -u meta.xml

EDIT (Taken from my comment below): I can't just load the file directly into the zip file by referencing the new version because the initial extraction is never being redirected to a file in my actual situation. Instead to a database where it undergoes some text processing in a background queue. It is then substituted back into the document on demand.

unix command-line-interface shell compression pipe

2 Answers

  1. Best Answer

    Is there a reason you can't just do:

    unzip -p sample.odt meta.xml
#modify meta.xml
zip sample.odt -u meta.xml
rm meta.xml

    Then you don't have to worry about doing wierd gyrations to pipeline everything back in

    In response to you comment, the only two suggestions I can think of is

    a) Write the file out to a random temp directory /tmp/<random_number>/meta.xml then do a zip sample.odt -u /tmp/<random_number>/meta.xml

    b) Ask on Stack overflow if there is a programatic way to manipulate your zip file.

    • 3

  2. The zip man page describes how a single dash can be used to represent STDIN or STDOUT in a command-line, so zip can be used in a pipeline.

    Look for Streaming input and output in the man page.

    BUT since you're using STDIN and not specifying a file name with this method, it's not going to work as you'd like with muti-file zip archives.

    As the mention of gunzip in the man page suggests, it's meant for archives containing single files.

    In the same way gzip filename produces filename.gz, zip can produce filename.zip except that zip requires you to explicitly name the zip file.

    HERE'S a relevant new post on SO. I nearly fell off my chair when I saw this.

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