there's no ldconfig cache either. So where does bash find libc?

For example, on the terminal I'm using, the right arrow outputs ^[[C. You can see what sequence your terminal outputs by pressing Ctrl-V Right Arrow. The same is true for other cursor-control keys such as Page Up and End.

If you kill ffmpeg process it will exit with code 255 (easily reproducible in the terminal)

man ps has all the answers, under the "PROCESS STATE CODES" heading:

In any case signal handling in shells is one of the least reliable and portable aspects. You'll find behaviours vary greatly between shells and often between different versions of a same shell. Be prepared for some serious hair pulling and head scratching if you're going to try to do anything non-trivial.

Both kill with a job specifier and terminal signals send to the entire process group, so both the shell and sleep.

As usual with almost any command, if you want a normal argument that starts with a - to not be interpreted as a switch, precede it with --

rkill command from pslist package sends given signal (or SIGTERM by default) to specified process and all its descendants:

PGID=$(ps opgid= "$PID") # get the Process Group ID

Typically, a process associated with a controlling terminal is foreground process and its process group is called foreground process group. When you start a process from the command line, it's a foreground process:

Quit the program by sending a different signal to both processes, e.g. SIGQUIT with Ctrl + \.

Why then sending the SIGINT manually to the shell doesn't kill the child, e.g. 'kill -2 <shell-pid>' doesn't do anything to a child process while Ctrl-C kills it?

The shell process itself is in yet another process group all of its own and so doesn't receive the signal when one of those process groups is in the foreground. It's that simple.

Switching "jobs" between foreground and background is (some details aside) a matter of the shell telling the terminal which process group is now the foreground one.

I am trying to understand how CTRL+C terminates a child but not a parent process. I see this behavior in some script shells like bash where you can start some long-running process and then terminate it by entering CTRL-C and the control returns to the shell. Could you explain how does it work and in particular why isn't the parent (shell) process terminated? Does the shell have to do some special handling of CTRL+C event and if yes what exactly does it do?

The CTRL-\ key sends a kill signal to the foreground job which, under normal circumstances, is guaranteed to terminate it. This signal cannot be captured by a process. However, this means the process cannot cleanup and is just summarily stopped. In some cases, a process can be stuck in a kernel wait state so this signal never reaches it. In that case, the process is unusable but cannot be killed.

Also, this code will fail if $$ is not the process group leader, such as when the script is run under strace. Since a call to setsid(2) is probably tricky from a shell script, one approach might be to ps and obtain the process group ID from that.

ps -o pid,pgid,stat,args

When your script starts a process, that child becomes a member of a process group with PGID equal to the PID of the parent process which is $$ in the parent shell.

To accomplish this, after starting the children (loop.sh) in the background, call wait, and upon receipt of the INT signal, kill the process group whose PGID equals your PID.

You need a trap in loop.sh. Traps are cleared for every subshell started unless they are explicitly trap ''SIG ignored by the parent.

ps --forest -o pid,tty,stat,time,cmd -g $(ps -o sid= -p 2795)

To get all the processes spawned by a process the whole tree needs to be built. I used awk for that. At first it builds a hash array to contain all PID => ,child,child... . At the end it calls a recursive function to extract all the child processes of a given process. The result is passed to another ps to format the result.

# Usage: run_with_timeout N cmd args... # or: run_with_timeout cmd args... # In the second case, cmd cannot be a number and the timeout will be 10 seconds. run_with_timeout () { local time=10 if [[ $1 =~ ^[0-9]+$ ]]; then time=$1; shift; fi # Run in a subshell to avoid job control messages ( "$@" & child=$! # Avoid default notification in non-interactive shell for SIGTERM trap -- "" SIGTERM ( sleep $time kill $child 2> /dev/null ) & wait $child ) }

Personally, I prefer signalling an error for invalid values

We can ask timeout to try to stop the program using SIGTERM, and to only send in SIGKILL if SIGTERM didn’t work. To do this, we use the -k (kill after) option. The -k option requires a time value as a parameter.

timeout_child () { trap -- "" SIGTERM; child=$!; timeout=$1; ( sleep $timeout; kill $child; ) & wait $child; } And the usage: ( while true; do echo -n .; sleep 0.1; done) & timeout_child 2

Instead of modifying /usr/share/applications/google-chrome.desktop, the file can be copied into ~/.local/share/applications/google-chrome.desktop and modified without root access. This file will take precedence over the global desktop file.

Systemd targets are reached once and do not fire again when the connection state changes. Depending how your network is managed there are a couple of options:

please, for the love of god do NOT use Mint as a source of inspiration for a derivative distro. If you like Cinnamon or Mate, fine, but holy CHRIST do not let your infrastructure get as criminally sloppy as Mint's. No unholy mixing of Debian and Ubuntu debs into some kind of Frankenbuntu, no namespace collisions, no ... well, no being Mint in general, please!Ideally, I really, really hope you'll continue to support Ubuntu as a primary platform, regardless of what you do with Pop!_OS. But hooboy, do not turn into another Mint, please.

If it was remotely possible to get Davinci Resolve running that would be incredible (and bring a lot of video people I think)

the most productive environment possible for people that use their computer to create.What is a productive environment?How do you measure productivity in an operating system environment?How do you compare YOUR distribution to other distributions when it comes to productivity?Is the way in which 'people that use their computer to create' (creators) the same across all professions and activities?Does a photographer have the same requirements for a productive environment as a software engineer?Why do you think your distribution will be the best for delivering a productive environment than any other Linux distribution?

And then think about if you want a rolling release, or a fixed release. Although all the distros you mentioned are on the fixed release side.

Think about how much you want to customize the desktop environment(DE), and whether you know how to do so. Pick a distro that has the DE you like.

There is no best distro. All of them are more or less the same.

When people talk about "beginner distros" they mean distros that are no hassle to get started, it doesnt mean they are somewhat inferior or less capable.

And honestly, most people prefer the no hassle, especially after wasting too much time dabbling with distros that are "for advanced users" troubleshooting all kinds of dumbass problems that just worked out of the box in many other distros.

considering PopOS is trying to tackle Ubuntu they really need their dual-boot setup to be a lot less tedious

The part where you want to add 2 EFI partitions is not advisable. It seems that Windows doesn't really like this, of you are dual booting multiple Linux installs it might work. But it is always recommended to use only 1 EFI partition per disk. Hope this helps. :)

You don't necessarily have to resize Windows' EFI partition. You can have multiple EFI partitions.

Make a 512MB fat32 partition during manual/custom PopOS install.Select its role as: "/boot/efi" in the PopOS installer.When the OS is installed, type sudo apt install refind and then it should automatically start the installer else type sudo refind-install. This will install rEFInd to your /boot/efi path.

Windows and Linux store their time in the BIOS differently, this will cause your clock to be desynchronized when you switch from one OS to the other. The easiest solution for it is to fix it in Linux, forcing it to work the same way as Windows. You can do this through the terminal:

We recommend the Alpine image as it is tightly controlled and small in size (currently under 5 MB), while still being a full Linux distribution. This is fine advice for Go, but bad advice for Python, leading to slower builds, larger images, and obscure bugs.

1) QT Apps load very slow in startup (ex, qpdfview, Audacious), had to look at Ubuntu forums to find a solution installing kvantum and KvYAru theme, so this is solved at the moment; but the theme (SVG based, cannot modify it in a text file) have orange highlights, not consistent with Mint-Y theme, but it is the best option at the moment. This temporary solution I found was here: https://itectec.com/ubuntu/ubuntu-qt-apps-are-very-slow-to-load-in-xubuntu-20-04-when-export-qt_qpa_platformthemegtk2-is-enabled/

We took a stance on an issue.

Pango is one of the most common font rendering libraries on Linux. It's used by GTK/GNOME and a lot of standalone apps, like Rofi, Polybar, and a lot of terminals.

cp src/glyphs/Symbols-2048-em\ Nerd\ Font\ Complete.ttf ~/.local/share/fonts fc-cache -fv pango-view -t "Playing some  for you right now"

Besides running contrary to the principles that lead a lot of people to Linux systems (a closed store that you can't alter...automatic updates you have no control over....run by just the one company)

Linux on the desktop won't take off until it is equally easy. Snap may be dumbed down, restricted and all the rest of it, but for ordinary users it's easier - and more secure - than the alternative.

>We do want Linux to be mainstream, don't we? Not at any cost.

Think about how native apps work in your favorite desktop operating system. Er, no, not that one. Think about your favorite popular desktop operating system.

Your operating system: Ubuntu 18.04.4 LTS

Welcome to Ubuntu!. It is good to ditch the Windows rubbish and get into the real OS where one can change anything you want, yet have a global community who can support the OS.

The best thing about an open source operating system, such as Linux, is that you can customize it as much as you want, ranging from default applications such as file managers, music players, web browsers, and text editors etc. to more vital system components such as the kernel, display managers, and terminal consoles. You can do this simply by downloading new application software and replacing the old ones with that, or editing system components by making changes in the source code of your operating system. The display manager is one such system component that you can replace simply by running a few commands mentioned in this article.

BlackArch is a Linux distribution designed for penetration testing and security research. You can think of it like Kali Linux, with the exception of being based on Arch Linux. Its official repositories contain more than +2500 various penetration testing tools, and hence it can be considered a very good option for anyone wishing to explore this field and try to hack their own phones/routers/devices during the quarantine time.

Redstar OS is a Fedora-based Linux distribution that was developed to empower all computers running in North Korea. Researchers from various independent teams verified that the distribution contains huge spying mechanisms and logging capability, beside some modified kernel modules to record everything done on the OS.

notifier_call_chain

rsync --info=progress2

Normally Ubuntu swaps files to disk frequently. Since the disk is a microSD card that's a bit slow and has limited write cycles, it's best to reduce swapping to only when needed.

Future kernel updates would require the updated kernels to be signed again, so it makes sense to put the signing commands in a script that can be run at a later date as necessary. A sample script /root/module-signing/sign-vbox-modules is given below.

Windows: Shift + Delete

Linux Memory Management at Scale

echo 256 > /proc/sys/fs/inotify/max_user_instances

Linux & Windows VPS

A shell script to automate the retrieval and installation of the Oracle (Sun) Java Runtime Environment

Download for macOS or Windows

To get a feel for how much pseudo-random data is available in your entropy pool, you can run this command:$ cat /proc/sys/kernel/random/entropy_avail 2684 The number shown appears to represent the number of bits of entropy that have been collected. Even 2,684 might not seem like much in a world in which we routinely speak in terms of terrabytes, but numbers above 100 are said to be a good sign. I

I'd like to offer my thoughts on ctime verses mtime. Sorry, but this will be a little verbose. First, if you change the contents of a file you change the mtime of a file. Since this is a change to the inode, ctime is updated as well. The mtime is bit like the date on a letter and ctime is a bit like the postmark on the envelope. You can set mtime to anything you want via the utime() system call or the touch command. Doing so sets the ctime and you cannot reset ctime. If you restored last year's payroll records from tape, you might want to set the mtime back to the end of last year. But the ctime will reliably still indicate when the last change to the file occurred. This is how your backup program will know that it must back up the file. The ctime is really used by backup program. But an application program that prints out a payroll listing would use mtime.

ctime indicates inode data change: ie. when you do chmod. chown on the file or when the file size changes. Not the contents of the file.

ctime refers to changes made to the file's inode (such as changing permissions, etc). mtime refers to changes to the data within the file. So cnewer will use a reference files inode change time for the comparision, whereas newer will use a reference files data modification time.

The main caveat to note is that it does use musl libc instead of glibc and friends, so certain software might run into issues depending on the depth of their libc requirements. However, most software doesn't have an issue with this, so this variant is usually a very safe choice.

See this Hacker News comment thread for more discussion of the issues that might arise and some pro/con comparisons of using Alpine-based images.

So be careful running editing a bash script that may be currently executing. It could execute an invalid command, or do something very surprising.

That app you desperately need in order to function? We probably have it. The vast software libraries of Ubuntu and Flatpak combine to make all of your tools available in a single location, called the Pop!_Shop.

QT_SCALE_FACTOR=1.34 application

I could probably bootstrap my way up from this with the C compiler to write a terrible editor, then write a terrible TCP client, find my way out to ftp.gnu.org, get wget, and keep going from there. Assume that documentation is plentiful. You want a copy of the Stevens book so you can figure out how to do a DNS query by banging UDP over the network? Done.

I use this to keep information about processes that were running at any time during last five days. These are 1-min snapshots so something might get lost but I think it is good enough for me. I want to have some data available when I discover there was a peak in resource usage (I use munin for that). I haven't found a better way to keep track of past processes (tried psacct).

Just remove the 'rb-readline' gem if you are on a linux like system.

Alternatively, if you want to modify the binary, try chrpath, which lets you edit the library search path baked in the executable.

/lib/libc.so.6

Now using sudo to work around the root account is not only pointless, it's also dangerous: at first glance rsyncuser looks like an ordinary unprivileged account. But as I've already explained, it would be very easy for an attacker to gain full root access if he had already gained rsyncuser access. So essentially, you now have an additional root account that doesn't look like a root account at all, which is not a good thing.

It is possible to do a successful file system migration by using rsync as described in this article and updating the fstab and bootloader as described in Migrate installation to new hardware. This essentially provides a way to convert any root file system to another one.

rsync provides a way to do a copy of all data in a file system while preserving as much information as possible, including the file system metadata. It is a procedure of data cloning on a file system level where source and destination file systems do not need to be of the same type. It can be used for backing up, file system migration or data recovery.

I am familiar with using rsync to back up various files from my system but what is the best way to completely restore a machine.

I run the script daily, early every morning, as a cron job to ensure that I never forget to perform my backups.

There are many options for performing backups. Most Linux distributions are provided with one or more open source programs specially designed to perform backups. There are many commercial options available as well. But none of those directly met my needs so I decided to use basic Linux tools to do the job.

CloneZilla works perfectly. It produces small image files, has integrity check and works fast. If you want to use third device as image repository you should choose device-image when creating image of the first disk and then image-device when you restore it to second disk. If you want to use only two disks - you should use device-device mode. Optionally you may want generate new UUIDs, SSH-key (if SSH server installed), and change hostname.

While there are so many tools to backup your systems, I find this method super easy and convenient, at least to me. Also, this method is way better than disk cloning with dd command. Because It doesn’t matter if your hard drive is different size, or use different filesystem.

provides a peek behind the ‘magic curtain’ at what is going on for a curious reader

Beginner's Guide to Installing from Source http://moi.vonos.net/linux/beginners-installing-from-source/