14
votes
7answers
2k 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
1answer
995 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 ...
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 ...
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 ...
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 ...
6
votes
6answers
731 views

How can I reproduce commands run on one machine on another machine?

I would like to install some software on a linux-machine that I have run in VirtualBox. Then I would like to do the same thing on a linux-VPS. I think that I can save all commands that I run using ...
15
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 ...
11
votes
5answers
12k 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 ...
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 ...
26
votes
3answers
8k views

Are there any side effects when two distros share a swap partition?

In order to save disk space, I want to have two OS installations share a single swap partition (a dual-boot). Is this a good idea?
18
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 ...
12
votes
2answers
886 views

Manipulating X key and pointer grabs on the command line

What command line tools exist to list and manage X server grabs? (That's grab as in key and pointer grabs, i.e. restricting the use of a particular key or mouse button to a particular application, or ...
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 ...
7
votes
3answers
29k views

Shell Script for logging into a ssh server

I tried writing a shell script which can do automatic login into a ssh server using password which is mentioned in the script. I have written the following code: set timeout 30 /usr/bin/ssh -p 8484 ...
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
2k 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 ...
2
votes
2answers
436 views

What information do I need to solve an APT dependency issue?

I've seen several times people with unmet dependencies, which apt-get doesn't tells straightforward what's the problem, like this one: The following packages have unmet dependencies: ...
12
votes
5answers
1k views

How to de-unzip, de-tar -xvf — de-unarchive in a messy folder?

Usually, I unarchive things by $ mkdir newFolder; $ mv *.zip newFolder; $ cd newFolder; $unzip *.zip but sometimes I get lazy and just do in an arbitrary folder $ unzip *.zip so time-to-time messing ...
4
votes
1answer
298 views

How to change the forgotten root password?

I am very new to Debian linux, I forgot my root password...actually I think I know what it is because it is the same password I have for pretty much everything but in the Terminal in tell me "Sorry, ...
3
votes
2answers
1k views

Installation on debian 5 32-bit without being a root

I am new to Linux and I am trying to install Skype and Google Chrome on my desktop. It runs Debian 5 32-bit. I downloaded the packages from the web but I have no idea how to install them. I have ...
4
votes
2answers
782 views

SSH tunnel through middleman server - how to connect in one step (using key pair)?

My question is basically how to turn my existing two steps into one step. I have a working SSH tunnel set up between two computers using a middleman server like this: ...
2
votes
3answers
7k views

Grub not loading after Windows 8 Install

My system was configured to dual boot Ubuntu 12.04.1 LTS and Windows 7. Today I got my hands on the MSDN release of Windows 8 and I installed it over my Windows 7. Now the computer just boots to ...
80
votes
1answer
91k views

How to set default file permissions for all folders/files in a directory?

I want to set a folder such that anything created within it (directories, files) inherit default permissions and group. Lets call the group "media". And also, the folders/files created within the ...
63
votes
3answers
32k views

What do the flags in /proc/cpuinfo mean?

How can I tell whether my processor has a particular feature? (64-bit instruction set, hardware-assisted virtualization, cryptographic accelerators, etc.) I know that the file /proc/cpuinfo contains ...
63
votes
26answers
11k views

Quick directory navigation in the terminal

I would like to frequently switch between directories that are in totally unrelated paths, for example /Project/Warnest/docs/ and ~/Dropbox/Projects/ds/test/. But I don't want to type cd ...
59
votes
9answers
2k views

Remember a half-typed command while I check something

I often find myself in the following position: I've started typing a long command at the bash prompt, but half-way through I find out I need to check something with another command. This is a problem ...
74
votes
6answers
20k views

Why hard links not allowed to directories in UNIX/Linux

I read in text books that UNIX/Linux doesn't allows hard links to directories but soft links do. Is it because, when we have cycles and if we create hardlinks, and after some time we delete the ...
23
votes
5answers
16k views

SSH to decrypt encrypted LVM during headless server boot?

When I installed Ubuntu 10.04 and, now, 10.10, I was offered the option of enabling "encrypted LVM" for my hard drive. After choosing that option, I am prompted for my password during boot to decrypt ...
26
votes
4answers
2k views

What are the responsibilities of each Pseudo-Terminal (PTY) component (software, master side, slave side)?

I am trying to figure out how a tty works1 (the work-flow and responsibilities of each elements). I have read several interesting articles about it, but there are still some blurry areas. This is ...
40
votes
6answers
7k views

The result of ls * , ls ** and ls ***

I know using the command ls will list all the directories. But what does the ls * command do ? I used it and it just lists the directories. Is the star in front of ls means how deep it can list the ...
31
votes
9answers
10k views

A tool for automatically applying RandR configuration when external display is plugged in

is there a tool which enables one to: remember current RandR configuration (position, orientation, resolution etc) on per-monitor basis, automatically apply last known good configuration as soon as ...
26
votes
4answers
7k views

Measuring RAM usage of a program

time is a brilliant command if you want to figure out how much CPU time a given command takes. I am looking for something similar that can measure the max RAM usage of the program and any children. ...
21
votes
2answers
6k views

How do I tell I'm running in a chroot?

I have a unix installation that's supposed to be usable both as a chroot and as a standalone system. If it's running as a chroot, I don't want to run any service (cron, inetd, and so on), because they ...
51
votes
3answers
3k views

How do the internals of sudo work?

How does sudo work internally? How is it possible that it can become root without having the root password, unlike su? What syscalls, etc. are involved in the process? Is it not a gaping security hole ...
19
votes
7answers
23k views

Which GUI diff viewer would you recommend, with Copy-to-Left/Right functionality?

I've hardly ever used anything other than Meld. Can you recommend anything else? It would be extra nice if you give a reason for your recommendation (as a Comment). [note] I want an alternative ...
15
votes
1answer
5k views

How can I configure a reverse SSH connection to the connecting computer?

I'm going to be deploying a number of machines in the near future which will be behind routers. It won't be feasible to set up dynamic DNS on each router and port forwarding, so is there a way I can ...
13
votes
5answers
48k views

How can I read line by line from a variable in bash?

I have a variable which contains multiline output of a command. What's the most effecient way to read the output line by line from the variable? For example: jobs="$(jobs)" if [ "$jobs" ]; then ...
13
votes
5answers
13k views

Show only stderr on screen but write both stdout and stderr to file

How can I use BASH magic to achieve this? I want to only see stderr output on the screen, but I want both stdout and stderr to be written to a file. Clarification: I want both stdout and stderr to ...
22
votes
8answers
22k views

Different ways to execute a shell script

There a several ways to execute a script, the ones I know are: /path/to/script # using the path (absolute or relative) . script # using the . (dot) source script # using the `source` command ...
12
votes
3answers
10k views

What is stored in /dev/pts files and can we open them?

According to my knowledge, /dev/pts files are created for ssh or telnet sessions.
23
votes
1answer
8k views

What does adduser do that useradd doesn't?

In addition to the more widespread useradd, Debian based systems also contain an additional adduser command which provides a higher level interface for adding users and some related tasks. There are ...
19
votes
3answers
8k views

How can I use two bash commands in -exec of find command?

Is it possible to use 2 commands in the -exec part of find command ? I've tried something like: find . -name "*" -exec chgrp -v new_group {} ; chmod -v 770 {} \; and I get: find: missing ...
17
votes
5answers
31k views

Script to monitor folder for new files?

How do I detect new files in a folder with a bash script? I would like to process the files as soon as they are created in the folder. Is this possible to do so or do I have to schedule a script with ...
25
votes
5answers
5k views

What process created this X11 window?

Given an X11 window ID, is there a way to find the ID of the process that created it? Of course this isn't always possible, for example if the window came over a TCP connection. For that case I'd ...
16
votes
2answers
7k views

/proc/PID/fd/X link number

In Linux, in /proc/PID/fd/X, the links for file descriptors that are pipes or sockets have a number, like: l-wx------ 1 user user 64 Mar 24 00:05 1 -> pipe:[6839] l-wx------ 1 user user 64 Mar 24 ...
15
votes
5answers
967 views

How to compile and install programs from source

This is an issue that really limits my enjoyment of Linux. If the application isn't on a repository or if it doesn't have an installer script, then I really struggle where and how to install an ...
35
votes
1answer
5k views

How to do a `tail -f` of log rotated files?

On a long running system I usually have a terminal with $ tail -f /var/log/kern.log or something like this open. But from time to time I have to restart such command because no new messages are ...
19
votes
5answers
4k views

Why is echo a shell built in command?

$ which echo echo: shell built-in command. $ which ls /bin/ls $ which cat /bin/cat Why is echo not an independent utility like ls, ps, cat etc? Why is it shell specific? Any good reasons?
20
votes
7answers
3k views

how to glob every hidden file except current and parent directory [duplicate]

I want to glob every hidden file and directory, but not the current (.) and parent directory (..). I am using bash. Observe current behaviour: $ ls -a . .. ...a ...aa ..a ..aa .a .aa .aaa ...

15 30 50 per page