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.
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…
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,…
crontab -e will start an editor to edit the crontab entries. But how to add a crontab entry from a shell script on Linux without interaction from users? You can try this piece of script: (crontab -l; echo “@reboot echo “rebooted””;) | crontab – Note that the update by this line of script is not…
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…
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…
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 ….
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
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…
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…
How to convert between Simplified Chinese and Traditional Chinese characters in text files on Linux from command line? You can use opencc to convert between Traditional Chinese and Simplified Chinese: https://github.com/BYVoid/OpenCC For example, to transfer a file in simplified Chinese sc.txt to traditional Chinese: opencc -i sc.txt -o tc.txt -c zhs2zht.ini The authors also provide…
dd seems slow when I use command like # dd if=/dev/sda2 of=./sda2.bak How to make it faster? You can make dd faster by specifying a good bs like # dd if=/dev/sda2 of=./sda2.bak bs=8192 8192 is a magic number. There are may be other good sizes for bs for different systems. But 8192 works pretty well…
What is a good basic iptables config? Basic rules needed: Allow incoming TCP to 22 for SSH but blocks all others. Allow outgoing TCP/UDP connections. You may consider using the following rules as a start: for tables in iptables ip6tables ; do # Flush existing rules $tables -F # Default policy $tables -P INPUT DROP…
How to log connections hitting certain rules in iptables on Linux? Like the one that are dropped because of too frequently creating SSH connections. You can create a new chain named LOGNDROP that log the connections and drop them, then pass the connection to be redirected to the LOGNDROP chain. $tables -N LOGNDROP # Connections…
How to configure iptables and make the configuration persistent across system restarting on Linux Mint 17.1? You can use the ‘iptables-persistent’ tool. To install iptables-persistency pachage: sudo aptitude install iptables-persistent The you can manipulate the iptables by the ‘iptables’ command. To save the current iptables rules: sudo /etc/init.d/iptables-persistent store It will store the rules for…
How to find the available packages’ versions with aptitude on Linux? With aptitude, you can use this command to show the available versions of a package: aptitude versions <package name> In the console GUI, aptitude also show the versions. You may also simulate installation of a package and see which version will be installed: aptitude…
How to exclude directories with certain names like “cache” from rsync on Linux during backup? The “cache” directory may in many different paths, such as file1/cache/ or file2/cache/, and adding all “cache” directories to rsync command is not a doable way. You can use rsync with –exclude=cache/ like rsync -avxP –exclude=cache/ /path/to/src/directory/ /path/to/dst/dir/
Currently, I have created my branch dev-harry but I cannot pull it successfully as follows. harryxiyou@common_vm ~/forest/kvplus/kvplus $ git branch * dev-harry master rc harryxiyou@common_vm ~/forest/kvplus/kvplus $ git pull You asked me to pull without telling me which branch you want to merge with, and ‘branch.dev-harry.merge’ in your configuration file does not tell me, either….
How to find the number of files in each sub-directories of a directory on Linux? For example, . ├── a19 ├── a8 ├── d2 ├── ecfddd └── t1 The number of sub-directories can be quite large. How to find the number of files in each sub-directories here? You can use this piece of script to…