Any suggestions on good open-source and free scanner software for Windows? NAPS2 (Not Another PDF Scanner 2) is my favorite opensource scanner software on Windows: http://naps2.sourceforge.net/ Scan documents to PDF and other file types, as simply as possible. NAPS2 is a document scanning application with a focus on simplicity and ease of use. Scan your…
I would like my site to be accessed by https only. How to force a website to use https by htaccess settings by redirecting http requests to the corresponding https ones? You can check the method of redirecting http to https at: https://www.systutorials.com/qa/1033/how-to-redirect-http-to-https-in-apache-with-mod_rewrite If you would like to have a 301 redirect, you can use…
A try like the following command failed $ sudo echo “echo hello” > /usr/local/bin/hello with an message bash: /usr/local/bin/hello: Permission denied It seems the writing to the file is executed under the non-root user. How to redirect STDOUT of sudo command on Linux and write the content to the file (/usr/local/bin/hello here) as root? You…
On a Linux box, we may allow non-root users mount and umount certain disks, such as /dev/sde1. How to allow non-root users on Linux to mount and unmount disks? Please check the tutorial at Controlling Filesystem Mounting on Linux by Playing with /etc/fstab: Allow non-root users to mount and unmount filesystems.
My laptop’s hard drive crashed. I went to someone else and got the hard drive replaced, but they could not recover my data. You may try PhotoRec as for https://www.systutorials.com/qa/1399/how-can-i-recover-deleted-photos-from-samsung . Although its named with “Photo”, PhotoRec can recover many kinds of files as listed in http://www.cgsecurity.org/wiki/File_Formats_Recovered_By_PhotoRec .
I can only connect to a Linux server by SSH. How to check whether a USB disk is connected to the Linux server? 2 ways I usuaully use: Method One: Check the print out of dmesg After the USB storage is connected and detected by Linux, it may print some messages containing “[sde]” (the new…
Any suggestions on good tutorials for screen on Linux? To start with screen: A quick tutorial on screen. After can use the basic functions of screen, you may check out A dummies introduction to GNU Screen and A guide to GNU Screen. During all the progresses, frequently check the screen man page.
How to convert all text in a file from upper case to lower case and vice versa on Linux? Convert from upper case to lower case: tr ‘[:upper:]’ ‘[:lower:]’ < input.txt > output.txt Convert from lower case to upper case: tr ‘[:lower:]’ ‘[:upper:]’ < input.txt > output.txt
Some entries in /etc/fstab may not not critical for booting Linux or even not available until Linux has booted. How to avoid the failures or unavailability of some mounting entries in /etc/fstab blocking the boot process of Linux? Please check the tutorial at Controlling Filesystem Mounting on Linux by Playing with /etc/fstab: Allow non-root users…
convert seems works not very well when merging PDFs. The quality is low. Any other better methods to merge multiple PDF files to a single PDF on Linux? ghostscript works the best for me on merging PDFs: gs -q -sPAPERSIZE=letter -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -dPDFSETTINGS=/prepress -sOutputFile=out.pdf in1.pdf in2.pdf in3.pdf merges in{1..3}.pdf to out.pdf.
Managing a cluster of servers, I would like to notified when a server is started. How to make the Linux servers email me or other admins automatically after they are started? I did this by adding a crontab entry on each servers like @reboot date | mailx -S smtp=smtp://smtp.example.com -s “`hostname` started” -r zma@example.com zma@example.com…
After a kernel panic, it is impossible to remotely connect to the Linux server to reboot it by SSH. How to make the panic kernel automatically reboot itself? Linux kernel has a nice feature that reboots itself after a timeout when a kernel panic happened. Usually, it is disabled by default. To turn it on,…
In hadoop I need to skip mapper function and directly execute the reducer function. We doing this to improve hadoop performance, if the hadoop framework is used to analyze same data sets, then mapper’s output will be same for different kind of jobs. To save the redundant computation for same results, I am planning to…
To get files with certain string in their file names, it is quite straightforward: ls *string* However, how to do the reverse one: how to get files without certain strings in their files names on Linux? You can get a list of file names by a combination of find and xargs as follows: find ….
Is it possible to set the replication factor for specific directory in HDFS to be one that is different from the default replication factor? This should set the existing files’ replication factors but also new files created in the specific directory. This can simplify the administration. We can set the replication factor of /tmp/ to…
On CentOS 6.6, I find that it can make the screen (console, not X) blank after a while. However, it does not power the screen off. This usually work on Fedora or other releases. I guess this is caused by some configurations specific in CentOS 6.6. How to make CentOS 6.6 power off the console…
I found CentOS 6.6 does not ship vbetool in its default repositories, EPEL or RPMfusion. How to install vbetool on CentOS 6.6? First, download the source package from http://www.codon.org.uk/~mjg59/vbetool/ and unpack the package. Second, install needed packages: # yum pciutils-devel pciutils-devel-static libx86-devel During the building, it will try to find the libpci.a in a different…
How to enable RPM Fusion for CentOS 6.6? Enable RPM fusion on RHEL 6 or compatible like CentOS: su -c ‘yum localinstall –nogpgcheck http://download1.rpmfusion.org/free/el/updates/6/i386/rpmfusion-free-release-6-1.noarch.rpm http://download1.rpmfusion.org/nonfree/el/updates/6/i386/rpmfusion-nonfree-release-6-1.noarch.rpm’ It will install https://fedoraproject.org/wiki/EPEL. If it fails to install EPEL automatically, you will need to install it manually. Reference: http://rpmfusion.org/Configuration
On Linux, how to delete a specific line from a text file in command line? For example, to delete the 4th line from a file aaa bbb ccc ddd eee ffffff You can use the “stream editor for filtering and transforming text” sed. With GNU sed: sed -i ‘4d’ ./file Here, -i means edit the…
How to convert .pptx slides to .jpg or .png images on Linux in command line? This following method works best for me. First, convert .pptx file to .pdf using libreoffice: libreoffice –headless –convert-to pdf file.pptx –headless makes libreoffice run in batch mode and not start the GUI. The pdf file will be named file.pdf by…