Tar a file with a different name

Question

To make my environment deployable, I occasionally tar up some handy files and scripts:

tar -czvf env.tgz .vimrc .vim/ bin/lsl bin/s

I would like to add .bashrc to the mix, but I have some sensitive information in there so I maintain .bashrc-deploy which I can then simply rename once the tarball is on the new server. However, I would really like to have the tarball have the correct name .bashrc from the get-go so that I would not have to rename. I considered writing a script which would temporarily rename the files and make the tarball, like so:

#!/bin/bash
mv .bashrc .bashrc-real
mv .bashrc-deploy .bashrc
tar -czvf env.tgz .bashrc .vimrc .vim/ bin/lsl bin/s
mv .bashrc .bashrc-deploy
mv .bashrc-real .bashrc

However, does tar have any internal way of storing someFile with the name anotherName in the tarball?

Answer 1

With pax (the standard (POSIX) command to create tar archives) and bsdtar see the -s option:

pax -s '/\.bashrc-deploy/.bashrc/' -w -x ustar . | gzip > a.tar.gz

bsdtar -s '/\.bashrc-deploy/.bashrc/' -zcf a.tar.gz .

Note however, that the above would replace the .bashrc-deploy string with .bashrc in any file path of any member to be added to the archive. If you want to replace only the ./.bashrc-deploy in the current directory, you'd have to write it:

pax -s '|^\./\.bashrc-deploy$|./.bashrc|' -w -x ustar .

(though from reading the POSIX pax specification, I'm not sure it's guaranteed to work that way with every pax implementation. It should work with bsdtar though as there's only one implementation).

Answer 2

One way you could do this is a chainload.

In .bashrc:

#!/bin/bash

# ...
# Non-private information
# ...

[[ -r ~/.bashrc-private ]] && . ~/.bashrc-private

Then put (only) your private stuff in ~/.bashrc-private and everything else in ~/.bashrc. Then just deploy ~/.bashrc.

Answer 3

With GNU tar (the default tar implementation on non-embedded Linux and on Cygwin):

tar czf env.tgz --transform 's/-deploy$//' .bashrc-deploy .profile …

This is also possible with pax, the POSIX replacement for cpio and tar, which unfortunately is missing from many default Linux installations, and also with BSD tar:

pax -w -x ustar '-s/-deploy$//' .bashrc-deploy .profile … | gzip >env.tgz
bsdtar -czf env.tgz '-s/-deploy$//' .bashrc-deploy .profile …

In all three cases, the s/REGEX/REPLACEMENT/ syntax is the same as ed or sed.

---

I question your approach. Having files with the same name but different contents on different machines is hard to maintain. Furthermore, it's easy to make a mistake if some files must remain private. My recommendation is to store your configuration files in subdirectories, and use symbolic links. For example, if .bashrc must be private and site-specific and .profile must be public and is the same everywhere:

.bashrc -> etc/local/private/.bashrc
.profile -> etc/.profile

Make etc/local a symbolic link to a directory whose name is site-dependent (e.g. ~/etc/home or ~/etc/work), ensure that ~/etc/private and ~/etc/*/private are only accessible by you, and you're set. You can deploy the whole ~/etc directory, and you'll only need to set the etc/local symbolic link after unzipping the archive (or, even better, checking out from version control).

For a file like .bashrc, which is probably mostly site-independent and public, split the file into two (or up to four) parts, public and private (plus site-specific files if necessary). Have the main part include the local parts:

if [ -e ~/etc/private/.bashrc ]; then . ~/etc/private/.bashrc; fi
if [ -e ~/etc/local/.bashrc ]; then . ~/etc/local/.bashrc; fi
if [ -e ~/etc/local/private/.bashrc ]; then . ~/etc/local/private/.bashrc; fi

In files which are written in a programming language, you can test the host name or domain name or other site-dependent characteristic dynamically, which lets you have a single file to maintain.

case $HOSTNAME in
  darkstar) alias foo=some-local-command;;
esac

It's a bit surprising to have confidential content in .bashrc. If you're defining environment variables, they belong in ~/.profile.