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1500 questions
616
votes
6 answers

Finding the PID of the process using a specific port?

I am installing hadoop on my Ubuntu system. When I start it, it reports that port 9000 is busy. I used: netstat -nlp|grep 9000 to see if such a port exists and I got this: tcp 0 0 127.0.0.1:9000 0.0.0.0:* …
wuchang
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605
votes
10 answers

How to force ssh client to use only password auth?

If I use pubkey auth from e.g.: an Ubuntu 11.04 how can I set the ssh client to use only password auth to a server? (just needed because of testing passwords on a server, where I default log in with key) I found a way: mv ~/.ssh/id_rsa…
LanceBaynes
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603
votes
25 answers

Repeat a Unix command every x seconds forever

There's a built-in Unix command repeat whose first argument is the number of times to repeat a command, where the command (with any arguments) is specified by the remaining arguments to repeat. For example, % repeat 100 echo "I will not automate…
dreeves
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601
votes
4 answers

Does curl have a --no-check-certificate option like wget?

I am trying to make a curl request to one of our local development servers running a dev site with a self-signed SSL cert. I am using curl from the command line. I saw some blog posts mentioning that you can add to the list of certificates or…
cwd
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588
votes
15 answers

What if 'kill -9' does not work?

I have a process I can't kill with kill -9 . What's the problem in such a case, especially since I am the owner of that process. I thought nothing could evade that kill option.
tshepang
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588
votes
9 answers

What is the difference between /opt and /usr/local?

According to the Filesystem Hierarchy Standard, /opt is for "the installation of add-on application software packages". /usr/local is "for use by the system administrator when installing software locally". These use cases seem pretty similar. …
Patches
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555
votes
7 answers

Scroll inside Screen, or Pause Output

I use screen for my command-line tasks while managing the servers where I work. I usually run small commands (mostly file-system tasks) but sometimes I run more extensive tasks (like DBA). The output of those tasks is important to me. Since I use…
AeroCross
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555
votes
27 answers

How can I resolve a hostname to an IP address in a Bash script?

What's the most concise way to resolve a hostname to an IP address in a Bash script? I'm using Arch Linux.
Eugene Yarmash
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551
votes
10 answers

How to append multiple lines to a file

I am writing a bash script to look for a file if it doesn't exist then create it and append this to it: Host localhost ForwardAgent yes So "line then new line 'tab' then text" I think its a sensitive format. I know you can do this: cat…
TheLegend
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538
votes
9 answers

How to display `top` results sorted by memory usage in real time?

How can I display the top results in my terminal in real time so that the list is sorted by memory usage?
Theodor Coogan
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534
votes
10 answers

Can less retain colored output?

Can I get less not to monochrome its output? E.g., the output from git diff is colored, but git diff | less is not.
ripper234
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530
votes
3 answers

What is a bind mount?

What is a “bind mount”? How do I make one? What is it good for? I've been told to use a bind mount for something, but I don't understand what it is or how to use it.
Gilles 'SO- stop being evil'
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527
votes
7 answers

How do I check package version using apt-get / aptitude?

Before I install a package, I'd like to know what version I would get. How do I check the version before installing using apt-get or aptitude on Debian or Ubuntu?
user4069
524
votes
11 answers

How do I copy a folder keeping owners and permissions intact?

So I was going to back up my home folder by copying it to an external drive as follows: sudo cp -r /home/my_home /media/backup/my_home With the result that all folders on the external drives are now owned by root:root. How can I have cp keep the…
Psachnodaimonia
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520
votes
7 answers

Can I zip an entire folder using gzip?

I'm trying to zip a folder in unix. Can that be done using the gzip command?
user1269502
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