debian HowTo - Linux / Unix Q & A from nixCraft

Linux: Hide Processes From Other Users

last updated August 21, 2014 in Linux, Security, User Management

I run a multi-user system. Most users access resources using ssh client. How to stop leaking process information to all users on Linux operating systems? How do I prevent users from seeing processes that do not belong to them on a Debian/Ubuntu/RHEL/CentOS Linux server?

Connect To Amazon AWS EC2 Instance From a CentOS / RHEL Using SSH Client

last updated June 23, 2014 in Amazon Cloud Computing, CentOS, Linux, OpenBSD, RedHat and Friends, UNIX

I have created/launched Amazon Machine Image (AMI) instance powered by a CentOS/RHEL/Red Hat Enterprise Linux. How can I connect to my instance using OpenSSH Linux/Unix/OSX ssh client?

Unix: Find Directory Name From Path

last updated April 7, 2014 in BASH Shell, KSH Shell, Linux, UNIX

I am a new Unix shell programer. How can I extract the directory name from a full path (say /nas01/data/backups/file.tar.gz)? How do I get directory name from its path on a Linux or Unix-like system?

scp: Do not Overwrite Existing File On Linux or Unix System

last updated May 10, 2013 in BASH Shell, Commands, Linux, UNIX

I am a new Linux user. I use scp to upload files to net-storage provided CDN company. I do not want to overwrite the existing files. How can I prevent overwriting of files when using scp command under Linux, Mac OS X or Unix like operating systems?

Vi / Vim: Wipe and Undo All Changes Since Opening a File

last updated April 28, 2013 in Linux, UNIX, Vim

I am a new vi / vim text editor user and I know how to quit without saving changes. What if I want to wipe out all of the edits I have made in a session and get back to the original file? How do I wipe all changes since opening a file?

Linux / Unix: Use rsync Command Over FTP

last updated April 9, 2013 in Linux, UNIX

How do I use rsync command to sync files to a remote host called web-42.vps running VSFTPD ftp server? Can you give me rsync ftp example for Unix like operating systems?

SSH: WARNING: UNPROTECTED PRIVATE KEY FILE! Error and Solution

last updated January 26, 2017 in Amazon Cloud Computing, Linux, Mac OS X, OpenBSD, Suse, Troubleshooting, UNIX

I‘m setting up server on an Amazon EC2 compute instance powered by Suse Enterprise Linux server. I am using the following command to login into the my EC2 compute from OS X/Ubuntu desktop:

ssh -i suse-ec2-server-jp.pem root@ec2-xx-yy-zzz-yyy.compute-1.amazonaws.com

I am getting the following error:
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ WARNING: UNPROTECTED PRIVATE KEY FILE! @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ Permissions 0440 for 'suse-ec2-server-jp.pem' are too open. It is recommended that your private key files are NOT accessible by others. This private key will be ignored. bad permissions: ignore key: suse-ec2-server-jp.pem Password:

How do I fix this problem and login using ssh command?