> Extract tar.gz in new directory: tar zxvf package.tar.gz -C new_dir
For quick reference, since it seems to be hard[1], these are the flags you'll most need in tar:
c = create
x = extract
v = verbose
z = gzipped; compressed.
f = file
So for example `tar xf example.tar` will extract that tar file. Or `tar cf example.tar .` will pack all files in the current directory to example.tar. For compression and verbosity, it would be `tar zvcf example.tar.gz .`. The .gz at the end is optional, but now others can see what kind of archive it is. Extract .tar.gz files with `tar xzf example.tar.gz`.
For bonus points, here is a poor man's version of scp/rsync:
Cheese note: I still do the ol' pipe dance when de-compressing archives, like this:
gunzip -c somefile.tar.gz | tar xvf -
The reason? Well, its like this: I learned it that way on machines that had, typically, about 4 megs available. So it used to be, back in the ol' days, that if you tried to do it like:
tar xvzf somefile.tar.gz
.. you'd run out of RAM, get into swapfile sadness, and so on.
Piping it through the console first, used the tty-buffers, which blocked whenever exhaustion occurs, but nevertheless: recovered a lot smoother than when heavy swap was involved ..
Dunno if its still 'true' (could be a mythos I'm passing on from the old, drunk sysadmin I learned the rule from) but it aways bugs me when I forget to do it 'the new way' ..
This is at least sometimes still true in corporate Linux environments. Giant, Immoral MegaCorps apparently can't be bothered to spring for big disks, so doing "tar xzf" or gunzipping something before un-tarring often fills up the filesystem. Embarassing, but true, given that you can hoof it to Office Depot and buy terabytes for a couple hundred, if they'd just let you.
Can't edit my post anymore, but good tip! As dmd commented though, it seems tar automatically detects compression on files because of the file extension.
Yesterday I got an error 'error: tar archive is compressed. Aborting' or something along those lines. When reading a file it might detect it because of the filename, but with stdin you need to specify the flag it seems.
Well, the default Linux shell is /bin/bash on most systems.
I'd say more about the article itself and what it should and/or does say on this, but at present, I suspect the author is looking up "Webserver and Database Scalability and Availability Tips & Tricks":
I'm well-aware that bash is a (if not the) popular choice on desktops and servers, but my terse and somewhat snarky answer was motivated by two other factors:
1. Not only do distributions like Debian or Ubuntu use dash, but various other shells are becoming more relevant to programmers due to their inclusion in special-purpose systems, such as devices running with a Busybox-userspace (which includes pretty much every Android phone, for instance).
2. If the article claims to have any educative value, it should definitely mention that this is something about a particular shell. Assuming the author isn't lying about his use of nix systems (since the diversity of shells is common knowledge to anyone seriously using Unices), the other logical choice is that saying bash instead of Linux isn't as cool in terms of SEO. The WWW is cluttered enough with every marketing drone hiring cheap labour on freelancer.com to fill it with bad spinoffs just to promote their semi-scam business, making any kind of legitimate information so hard to find you'd think it's 1998 again for some topics; it itches me on a personal* level when I see programmers doing that. We should know better.
A number of Linux distributions have moved to the BSD-licensed dash[1] for running their system initialization scripts, as it's noticeably faster than bash (resulting in faster boot times). Ubuntu made this change back in 2006 [2][3], and Debian switched to dash for Debian Squeeze.
Bash is still the default user shell on those systems, though.
This is incorrect and misleading right off the bat. Ctrl+Z does not "send process to background." You will almost always need to use the bg command for that after suspending the running program.
Came here to say that and to add. Long list of commands with no explanation or details is minimally useful.
I challenge you to read a man page a week. Use that command every day that week. Find away to use it with two or three other commands you know. Breakdown tasks into units the size of commands you know. Fill in missing pieces with bash or scripting language of choice.
I've been using Linux since 2006... And only this year did I finally type 'man' into my terminal. I no longer use google for finding those sorts of things out.
Content is typical blog style content and even comments come from Disqus, so ther should not be any reason to connect to a database with every request.
Nice list of stuff, especially for people relatively new to command line stuff
there's a cool twitter account called "Command Line Magic" (https://twitter.com/climagic) that does some fun stuff, and is pretty shell-agnostic.
Also, for those willing to, I'd strongly suggest checking out fish. it's not bash-compatible, but there's a lot of good usability aspects to it (especially compared to vanilla bash), I love it.
Out of curiosity though, this command :
tar zxvf package.tar.gz -C new_dir
it's always intrigued me that the tar command (I imagine it is mainly used to "unzip" things) does not make it very simple to do this. I've started to memorize the 4-letter combo but for a while I had to google it everytime (man pages are not useful for learning things for a lot of unix cl tools).
tar is not a compression program per se, but a file archiving tool. It is used because it preserves file system information such as permissions, owner and group, which would otherwise be lost if you used zip/gzip/bzip alone. Each letter has a meaning, x is for extract, f is file, v is verbose (print details to screen) and f is for file. So the cryptic four letters are really easy to rememeber: eXtract the Zip File Verbosely. Change the x for a c (Create) and you can make a new file.
I was going to ask what is wrong with the man page (because in my experience they do a mighty fine job of explaining most traditional unix tools). But then I checked the manuals for two variants of tar (gnu and obsd), and I can see how they might appear less than helpful for a new user who has never dealt with gzip before.
I am surprised the xz(v)f invocation isn't in the examples. I could've sworn it's there...
> it's always intrigued me that the tar command (I imagine it is mainly used to "unzip" things) does not make it very simple to do this.
It helps to remember that tar stands for Tape ARchiver (or Tape ARchive, or something, depending on who you ask), and that its interface really does date from the era when dealing with tape was a common task for pretty much any sysadmin.
Readit News
For quick reference, since it seems to be hard[1], these are the flags you'll most need in tar:
So for example `tar xf example.tar` will extract that tar file. Or `tar cf example.tar .` will pack all files in the current directory to example.tar. For compression and verbosity, it would be `tar zvcf example.tar.gz .`. The .gz at the end is optional, but now others can see what kind of archive it is. Extract .tar.gz files with `tar xzf example.tar.gz`.For bonus points, here is a poor man's version of scp/rsync:
[1] Obligatory xkcd https://xkcd.com/1168/Edit: replaced all asterisks with a period (.) since it would become italics. Tar is recursive by default, so it should work the same.
Piping it through the console first, used the tty-buffers, which blocked whenever exhaustion occurs, but nevertheless: recovered a lot smoother than when heavy swap was involved ..
Dunno if its still 'true' (could be a mythos I'm passing on from the old, drunk sysadmin I learned the rule from) but it aways bugs me when I forget to do it 'the new way' ..
Same here. Old habits die hard, I suppose.
e.g.
tar axf linux.tar.gz
tar axf linux.tar.bz2
tar axf linux.tar.xz
will all work, assuming you have gzip, bzip2 and xz installed.
j = bzip2
I find a lot of packages with the `.tar.bz2' extension. Just replace `z' with `j' in your tar command and you're good.
Deleted Comment
I hate to be overly pedantic, but what shell would that be? There is no such thing as the Linux shell.
I'd say more about the article itself and what it should and/or does say on this, but at present, I suspect the author is looking up "Webserver and Database Scalability and Availability Tips & Tricks":
"Error establishing a database connection"
1. Not only do distributions like Debian or Ubuntu use dash, but various other shells are becoming more relevant to programmers due to their inclusion in special-purpose systems, such as devices running with a Busybox-userspace (which includes pretty much every Android phone, for instance).
2. If the article claims to have any educative value, it should definitely mention that this is something about a particular shell. Assuming the author isn't lying about his use of nix systems (since the diversity of shells is common knowledge to anyone seriously using Unices), the other logical choice is that saying bash instead of Linux isn't as cool in terms of SEO. The WWW is cluttered enough with every marketing drone hiring cheap labour on freelancer.com to fill it with bad spinoffs just to promote their semi-scam business, making any kind of legitimate information so hard to find you'd think it's 1998 again for some topics; it itches me on a personal* level when I see programmers doing that. We should know better.
Bash is still the default user shell on those systems, though.
[1]: https://en.wikipedia.org/wiki/Debian_Almquist_shell
[2]: http://lwn.net/Articles/343924/
[3]: https://wiki.ubuntu.com/DashAsBinSh
I challenge you to read a man page a week. Use that command every day that week. Find away to use it with two or three other commands you know. Breakdown tasks into units the size of commands you know. Fill in missing pieces with bash or scripting language of choice.
Ctrl Z is stop/suspend, unless the application has handling for that signal (e.g. lftp)
Now off to learn about disown, dtatch and nohup
`jobs` might be useful to you as well, in that case.
I'm sure somebody will find something useful here though.
Here's a Google Cache link: http://webcache.googleusercontent.com/search?q=cache:5z9gUWv...
Content is typical blog style content and even comments come from Disqus, so ther should not be any reason to connect to a database with every request.
Maybe author is using a free edition which has limit?
there's a cool twitter account called "Command Line Magic" (https://twitter.com/climagic) that does some fun stuff, and is pretty shell-agnostic.
Also, for those willing to, I'd strongly suggest checking out fish. it's not bash-compatible, but there's a lot of good usability aspects to it (especially compared to vanilla bash), I love it.
Out of curiosity though, this command : tar zxvf package.tar.gz -C new_dir
it's always intrigued me that the tar command (I imagine it is mainly used to "unzip" things) does not make it very simple to do this. I've started to memorize the 4-letter combo but for a while I had to google it everytime (man pages are not useful for learning things for a lot of unix cl tools).
I am surprised the xz(v)f invocation isn't in the examples. I could've sworn it's there...
man is obviously useful when you want to know what one switch does, but there are a lot of tools that could use an introductory "how to use"
It helps to remember that tar stands for Tape ARchiver (or Tape ARchive, or something, depending on who you ask), and that its interface really does date from the era when dealing with tape was a common task for pretty much any sysadmin.