11
votes
3answers
7k views

How to find out which (not installed) package a file belongs to?

On Debian systems (and derivatives): $ dpkg --search /bin/ls coreutils: /bin/ls That is, the file /bin/ls belongs to the Debian package named coreutils. But this only works if the package is ...
7
votes
2answers
2k views

Find filesystem of an unmounted partition from a script

I'm writing a custom automated install using AIF (Arch Installation Framework), and I need to find the filesystem on a partition given a partition. So far I have this: grok_partitions () { local ...
7
votes
2answers
10k views

Extracting a regex matched with 'sed' without printing the surrounding characters

To all the 'sed' doctors out there: I have a seemingly trivial 'sed' question to which I have not been able to find a solution. How can you get 'sed' to exctract a regular expression it has matched ...
7
votes
2answers
5k views

ssh port forward to access my home machine from anywhere

http://serverfault.com/questions/303937/how-to-make-freebsd-box-accessible-from-internet I want to understand this whole process of port forwarding. I read so many things but failing to understand ...
6
votes
2answers
8k views

Why is my variable being localized in one 'while read' loop, but not in another seemingly similar loop [duplicate]

Why do I get different values for $x from the snippets below? #!/bin/bash x=1 echo fred>junk ; while read var ; do x=55 ; done <junk echo x=$x # x=55 .. I'd expect this result x=1 cat ...
4
votes
6answers
19k views

Changing extension to multiple files

I would like to change file extension from *.txt file to *.text file, tried using the basename command, but I am having trouble on changing more than 1 file, I am getting a basename: too many ...
30
votes
3answers
4k views

What does size of a directory mean in output of 'ls -l' command?

What does size of a directory mean in output of ls -l command?
11
votes
6answers
741 views

How can I cleanly add to $PATH?

I'd like a way to add things to $PATH, system-wide or for an individual user, without potentially adding the same path multiple times. One reason to want to do this is so that additions can be made ...
7
votes
3answers
719 views

Linux Bulk/Remote Administration

Beside our internal IT infrastructure, we've got around 500 Linux machines hosting our services for the on-line world. They are grouped in a bunch of clusters like Database A-n, Product A-n, NFS, ...
8
votes
4answers
267 views

Is LILO still usable on modern PC?

How does LILO work on modern hardware with today's kernels? Do I have to fulfill any preconditions, or is it just about writing the configuration file and running lilo command like in the old days? ...
4
votes
2answers
902 views

undelete files from local fileserver

I have a NAS (mybook world white light) in my living room where all my music and stuff is stored. I've mounted the music folder of the nas in the local music folder of my home directory on my desktop ...
3
votes
1answer
2k views

Rename All Files with a Certain Name

I'm trying to find certain files with the name "stringx" and replace the name (but not the extension) with "stringy". So basically for stringx.txt and stingx.cs, I'd want stringy.txt and stringy.cs. ...
119
votes
4answers
20k views

/usr/bin vs /usr/local/bin on Linux

Why are there so many places to put a binary in Linux? There are atleast these five: /bin/ /sbin/ /usr/bin/ /usr/local/bin/ /usr/local/sbin/ And on my office box, I do not have write permissions ...
146
votes
2answers
29k views

Difference between nohup, disown and &

What is the difference between $ nohup foo and $ foo & and $ foo & $ disown
86
votes
7answers
12k views

Which is the safest way to get root privileges: sudo, su or login?

I would like to have the root account in safety even if my unprivileged user is compromised. On Ubuntu you can only use sudo for "security reasons" by default. However I am not sure it is any safer ...
42
votes
11answers
17k views

Recommended reading to better understand Unix/Linux internals [closed]

I've worked on *nix environments for the last four years as a application developer (mostly in C). Please suggest some books/blogs etc. for improving my *nix internals knowledge.
66
votes
2answers
38k views

Getting 256 colors to work in tmux

I have 256 colors working just fine in konsole,. I thought I'd give tmux a try because, unlike screen, it seems to support vi mode. However I find that the colors of my prompt show up and this is ...
29
votes
10answers
16k views

Correct locking in shell scripts?

Sometimes you have to make sure that only one instance of a shell script is running at the same time. For example a cron job which is executed via crond that does not provide locking on its own (e.g. ...
27
votes
2answers
16k views

Do the parent directory's permissions matter when accessing a subdirectory?

If I have a root folder with some restrictive permission, let's say 600, and if the child folders/files have 777 permission will everybody be able to read/write/execute the child file even though the ...
34
votes
5answers
14k views

How to check if a shell is login/interactive/batch

I think I understand the differences between an interactive, a login and a batch shell. See the following links for more help: What is the difference between a 'Login' and an 'Interactive' bash ...
29
votes
4answers
2k views

Is there a one-liner that allows me to create a directory and move into it at the same time?

I find myself repeating a lot of: mkdir longtitleproject cd longtitleproject Is there a way of doing it in one line without repeating the directory name? I'm on bash here.
38
votes
4answers
37k views

How big is the pipe buffer?

As a comment in I'm confused as to why "| true" in a makefile has the same effect as "|| true" user cjm wrote: Another reason to avoid | true is that if the command ...
28
votes
5answers
5k views

Why do hard links exist?

I know what hard links are, but why would I use them? What is the utility of a hard link?
26
votes
7answers
27k views

Correctly determining memory usage in Linux

I'm a bit confused on some of the results I am seeing from "ps" and "free". On my server, this is the result of "free -m" [root@server ~]# free -m total used free shared ...
21
votes
6answers
19k views

Lightweight outgoing SMTP server

What do you use as a lightweight SMTP for outgoing e-mails only? I am running an app that sends e-mails via SMTP when events occur once in a while, and I don't need a fully featured e-mail server. ...
31
votes
5answers
21k views

How to speed my too-slow ssh login?

Running ssh user@hostname takes ~30s. Here's the scenario: this is a VM on the local LAN Windows and Mac machines get instant login am using Debian and I could reproduce with an Ubuntu machine ...
9
votes
4answers
6k views

How do I handle switches in a shell script?

Are there some built-in tools that will recognize -x and --xxxx as switches, and not arguments, or do you have to go through all the input variables, test for dashes, and then parse the arguments ...
24
votes
7answers
6k views

What Unix commands can be used as a semaphore/lock?

I want to run multiple Bash shell scripts in parallel. However, I want to avoid race conditions. What Unix commands are truly atomic that I could use for this purpose, and how can I use them?
10
votes
2answers
45k views

Can I resize the root partition without uninstalling and reinstalling Linux (or losing data)?

I have started using a machine that has both Debian and Windows 7 installed. However, after installing some programs I started getting a message that there is not enough space. I knew that the system ...
13
votes
2answers
2k views

Correctly setting environment

I'm using zsh and gdm to run gnome. Some time ago I discovered that variables are not set correctly. For example LANG/LC_ALL are incorrect ("" instead of en_GB.UTF-8). I split the .zshrc into .zshrc ...
14
votes
5answers
3k views

Getting information on a machine's hardware in Linux

How can I check what hardware I have? (With BIOS version etc.)
27
votes
5answers
9k views

Is Mac OS X UNIX?

I have this argument recently saying Mac OS X was not UNIX, but Unix-like. I know there is a Single Unix Specification and those spec complaint could use the UNIX trade mark. Is Mac OS X an UNIX ...
12
votes
9answers
6k views

Ensure a process is always running

I started hosting sites a while back using Cherokee. For external sources (FastCGI, etc) it has an option to launch the process if it can't find one running on the designated socket or port. This is ...
8
votes
1answer
3k views

Where should a local executable be placed?

I have an executable for the perforce version control client (p4). I can't place it in /opt/local because I don't have root privileges. Is there a standard location where it needs to be placed under ...
31
votes
4answers
3k views

unix, difference between path starting with '/' and '//'

In unix/linux, any number of consecutive forwardslashes in a path is generally equivalent to a single forwardslash. eg. $ cd /home/shum $ pwd /home/shum $ cd /home//shum $ pwd /home/shum $ cd ...
18
votes
1answer
2k views

Run a command for a specified time and then abort if time exceeds

I want know how I can run a command for a specified time say, one minute and if it doesn't complete execution then I should be able to stop it.
14
votes
7answers
1k views

How can I prepend a tag to the beginning of several files?

I need to add PHP tags surrounding a file. It's easy to append them using find . -exec echo "?>" >> '{}' \; but how can I prepend the tag <?php?
11
votes
8answers
2k views

How can I build a custom distribution for running a simple web browser?

You'll have to forgive me, as I'm relatively new at doing something like this, but I need to do the following and I know that it has and can be done. Basically, a few friends and me are assembling ...
10
votes
1answer
949 views

Why is my bash prompt getting bugged when I browse the history?

Often when I start looking at history of commands some of the characters from a command displayed aren't erased, for example: What's happening: prompt$ some_command prompt$ some_commanother_command ...
8
votes
2answers
8k views

Bash Script on Startup? (Linux)

Is there any way to make/run a bash script on reboot (like in Debian/Ubuntu for instance, since thats what my 2 boxes at home have) Also, any recommended guides for doing cron jobs? I'm completely ...
14
votes
4answers
5k views

Make `rm` move to trash

Is there a Linux script / application which, instead of deleting files, moves them to a special “trash” location? I’d like this as a replacement for rm (maybe even aliasing the latter; there are pros ...
12
votes
1answer
7k views

What is meant by mounting a device in Linux?

I've heard the term "mounting" when referring to devices in Linux. What is its actual meaning? How it handling now unlike older versions? I haven't done that manually via the command-line. Can you ...
11
votes
5answers
11k views

Remove comma between the quotes only in a comma delimited file

I have a input file delimited with commas (,). There are some fields enclosed in double quotes that are having a comma in them. Here is the sample row 123,"ABC, DEV 23",345,534.202,NAME I need to ...
9
votes
1answer
4k views

How can I make variables “exported” in a bash script stick around?

I have multiple Amazon EC2 accounts and want to quickly be able to switch variables, such as $EC2_HOME, using a script. I have have a shell script set up like this: #!/bin/sh export ...
7
votes
2answers
2k views

How to restrict internet access for a particular user on the lan using iptables in Linux

Let's say there are two users on the LAN, A and B. How do I restrict user A from internet access using iptables rules and saving the rules so that after reboot, they are still effective. And suppose I ...
7
votes
2answers
1k views

In `while IFS= read..`, why does IFS have no effect?

I might have something absolutely wrong, but it looks convincing to me, that setting IFS as one of the commands in the pre-do/done list has absolutely no effect. The outer IFS (outside the while ...
17
votes
1answer
2k views

Is there a way in bash to redirect output and still have it go to stdout?

Okay. If I wanted to redirect the output of a program to a file, I'd do something like this prog > file If I wanted to redirect both stdout and stderr to that file, then I'd do prog > file ...
8
votes
2answers
3k views

Creating a UNIX account which only executes one command

Is there a way to create a user account in Solaris which allows the users to run one command only? No login shell or anything else. I could possibly do it with /usr/bin/false in /etc/passwd and just ...
4
votes
4answers
2k views

How to recover a file just deleted [duplicate]

I just deleted a file in Nautilus with Shift+Delete, which warned me that "If you delete an item, it will be permanently lost." I wonder if there is no way to recover the file? My OS is Ubuntu 10.10. ...
4
votes
1answer
1k views

Reading a filesystem from a whole disk image

I ran these commands: VBoxManage clonehd d6b9f0a5-98df-48ca-83c8-91a0809ec349 --format RAW Debian.raw sudo dd if=~/.VirtualBox/HardDisks/Debian.raw of=/dev/sda5 When I try to mount the partition, I ...

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