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1500 questions
87
votes
5 answers

What is the difference between 'nobootwait' and 'nofail' in fstab?

In this question I asked how to prevent a media failure from halting the system boot process. However, I got two suggestions for /etc/fstab options nobootwait nofail What is the difference between the two?
Evan Carroll
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87
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3 answers

What is the bash shortcut to change to the previous directory?

Sadly, I only learned about this last year by stumbling upon it randomly on the internet. I use it so infrequently that I always forget what it is by the time I need it again. How do you change to your previous directory?
hobodave
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87
votes
3 answers

Shell: how to go to the beginning of line when you are inside a screen?

I am inside a screen (screen -Ra). I have a long command, and I am at the end. Instead of keeping the left arrow, how can you go to the beginning of the line? CTRL-A works when I am in a normal window, but when I am inside a screen pressing CTRL-A…
user11498
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87
votes
5 answers

Refresh env variables after editing bashrc file

I frequently edited the .bashrc file to export new environment variables. Rather than close the console and start a new one to refresh the env variables, is there a convenient way to refresh?
xiaohan2012
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87
votes
11 answers

Is it good to make a separate partition for /boot?

I've seen some people make a separate partition for /boot. What is the benefit of doing this? What problems might I encounter in the future by doing this? Also, except for /home and /boot, which partitions can be separated? Is it recommended?
Am1rr3zA
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87
votes
4 answers

How to close (kill) ssh ControlMaster connections manually

With the following .ssh/config configuration: ControlMaster auto ControlPath /tmp/ssh_mux_%h_%p_%r ControlPersist 4h How to close the persisting connection before the 4 hours? I know you can make new connections, but how to close them (all)? Maybe…
Paolo
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87
votes
2 answers

Nslookup: command not found error on RHEL/CentOS 7

During linux installation I selected "minimal" option: When I went to run the nslookup command to look up an IP address I got the error message nslookup: command not found as shown in the example below. $ nslookup www.google.com bash: nslookup:…
Anthony Ananich
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87
votes
4 answers

How can I echo dollar signs?

For example, $PATH and $HOME When i type echo $PATH it returns my $PATH, but i want to echo the word $PATH and not what the actual variable stands for, echo "$PATH" doesn't work either.
DisplayName
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87
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4 answers

Recursive grep vs find / -type f -exec grep {} \; Which is more efficient/faster?

Which is more efficient for finding which files in an entire filesystem contain a string: recursive grep or find with grep in an exec statement? I assume find would be more efficient because you can at least do some filtering if you know the file…
Gregg Leventhal
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87
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4 answers

How do I update GRUB in Arch Linux

In Ubuntu, we use this command to update GRUB: # update-grub But how do I update GRUB version 2.00 in Arch Linux?
Hamed Kamrava
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86
votes
3 answers

How do the internals of sudo work?

How does sudo work internally? How is it possible that it can become root without having the root password, unlike su? What syscalls, etc. are involved in the process? Is it not a gaping security hole in Linux (e.g. why couldn't I compile a…
strugee
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86
votes
2 answers

Replacing string based on line number

I have a situation where i want to replace a particular string in many files Replace a string AAA with another string BBB but there are lot of strings starting with AAA or ending in AAA ,and i want to replace only one on line 34 and keep others…
krypto
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86
votes
6 answers

How to loop over the lines of a file?

Say I have this file: hello world hello world This program #!/bin/bash for i in $(cat $1); do echo "tester: $i" done outputs tester: hello tester: world tester: hello tester: world I'd like to have the for iterate over each line individually…
Tobias Kienzler
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86
votes
2 answers

Why has Raspbian apparently been renamed into "Raspberry Pi OS"?

I was making some routine checks just now and realized this: Raspberry Pi OS (previously called Raspbian) Source: Raspberry Pi OS I found no mention of this in their blog, nor on the Wikipedia page. Why change such a good name as "Raspbian" into…
Rithy
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86
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7 answers

How to view a TTF font file?

Is there an application to simply preview a font from a TTF file without installing it?
Ivan
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