≡ Menu

Linux

Bash Check If Shell Is Interactive or Not Under Linux / Unix Oses

How do I check in GNU/Bash if a shell is running in interactive mode or not while writing shell scripts?
[click to continue…]

Grep Include Only *.txt File Pattern When Running Recursive Mode

I‘m using Debian Linux as my development workstation. I would like to search a directory called ~/projects/ recursively for “foo” word only for *.txt files. How do I search all text files in ~/projects/ for “foo” word using grep command?
[click to continue…]

HowTo: Use Grep Command In Unix / Linux To Search Subdirectories

I would like to search and find all files which contain a word called “main()” for all directories located in $HOME/project/school. How do I use the grep command to find text including all subdirs under Unix or Linux operating systems?
[click to continue…]

HowTo: Revoke OpenSSH Keys and Disable User Access

Many users are using ssh to log into a remote machine and append the indicated identity file to machine’s ~/.ssh/authorized_keys file. I recently moved one of my server, and I would like to revoke openssh keys and disable user access under Linux operating systems. How do I revoke OpenSSH keys under Unix or Linux operating systems?
[click to continue…]

Linux / Unix: sed Command Print Only Matching Lines

I see many examples and man pages on how to do operations like search-and-replace using sed. But, I want to match a given string or a regular pattern expression and display on the screen. How do I print lines with matching pattern using sed command only under Unix like operating systems?
[click to continue…]

Synology Nas: Run Fsck To Check and Repair a Linux File System

I own a Linux powered Synology dedicated Network Attached Storage (NAS) server for my home office use. How do I run fsck on Synology DiskStation that offers RAID storage using Linux command line options over an ssh session?
[click to continue…]

Unix / Linux: Maximum Character Length of Arguments In a Shell Command

What is the maximum character length of arguments in a shell command? How do I find out the maximum length of arguments for a new process under Linux or Unix like operating systems?
[click to continue…]

Linux / Unix: Find Out DNS Server IP Address / Names

How do I find out my DNS server IP address assiged my my ISP under Unix or Linux operating system using command prompt? How do I find preferred dns server under Debian / Ubuntu / Fedora Linux desktop system?
[click to continue…]

Linux: warning: CUPSEXT could not be loaded. Please check HPLIP installation.

I‘m trying to install latest version of Hewlett-Packard’s Linux Imaging and Printing software (HPLIP) for my office jet printer. In order to install latest version of HPLIP I removed the hplip-gui, hplip, hplip-cups, hplip-data, hpijs, and hpijs-ppds Debian Linux packages However, I’m getting the following error:

Debian warning: CUPSEXT could not be loaded. Please check HPLIP installation.

How do I fix this error while installing hplip-3.12.9.run under Debian Linux 6.0.5 amd64 bit?
[click to continue…]

awk: warning: escape sequence '\<' treated as plain '>'

I‘m trying to match words using GNU awk command and getting the following error:

echo 'foo bar this that blah' | awk '{gsub("\<regex-word\>", "NEW-WORD");print}'

But getting the following warning on screen and it is not working:
awk: warning: escape sequence `\< ' treated as plain `<' awk: warning: escape sequence `\>' treated as plain `>'

How do I fix this problem under Unix like operating systems?
[click to continue…]