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1500 questions
79
votes
7 answers
Parenthesis in expr arithmetic: 3 * (2 + 1)
expr does not seem to like parenthesis (used in mathematics to explicit operator priority):
expr 3 * (2 + 1)
bash: syntax error near unexpected token `('
How to express operator priority in bash?
Nicolas Raoul
- 8,205
79
votes
3 answers
How do I find out if my wireless card supports 5 GHz?
I have the
03:00.0 Network controller: Intel Corporation Centrino Wireless-N 2200 (rev c4)
How do I find out if that card/driver support 5 GHz?
Evan Carroll
- 30,763
- 48
- 183
- 315
79
votes
2 answers
Will Linux start killing my processes without asking me if memory gets short?
I was running a shell script with commands to run several memory-intensive programs (2-5 GB) back-to-back. When I went back to check on the progress of my script I was surprised to discover that some of my processes were Killed, as my terminal…
NeutronStar
- 1,671
79
votes
3 answers
How do I run 32-bit programs on a 64-bit Debian/Ubuntu?
I have a 64-bit (amd64 a.k.a. x86_64) Debian or Ubuntu installation. I need to run 32-bit (i386/i686) programs occasionally, or to compile programs for a 32-bit system. How can I do this with a minimum of fuss?
Bonus: what if I want to run or test…
Gilles 'SO- stop being evil'
- 829,060
79
votes
5 answers
Is it possible to save as root from nano after you've forgotten to start nano with sudo?
A lot of the time I edit a file with nano, try to save and get a permission error because I forgot to run it as root. Is there some quick way I can become root with sudo from within the editor, without having to re-open and re-edit the file?
Kit Sunde
- 4,504
- 10
- 31
- 34
79
votes
4 answers
echo bytes to a file
I'm trying to connect my rasberry Pi to some display using the i2c bus.
To get started I wanted to manually write stuff, bytes in particular to a file.
How do you write specific bytes to a file?
I already read that one and I figured my problem…
Mark
- 1,169
79
votes
5 answers
Becoming root from inside Vim
Sometimes I start editing configuration files in /etc using Vim, but forget to use sudo to start Vim. The inevitable result then is that after finishing my edits I encounter the dreaded notice that I don't have the permission to save the file.…
Mad Scientist
- 1,256
79
votes
9 answers
How to find out which file is currently opened in vim?
This may sound trivial but, on more than one occasion, I have found myself having forgotten which file in vim I have open (e.g. when I am looking through different log files and such) and the only way I knew how to find out was to close the file and…
amphibient
- 12,472
- 18
- 64
- 88
79
votes
4 answers
How to find power draw in watts?
I've been asked to estimate the power consumption of the servers I run for my laboratory. I thought that I'd ask if there was some handy Linux commandline to get the power consumption of the server. It looks like powertop is useful for minimizing…
speciousfool
- 937
79
votes
1 answer
How do I force remove a package in Arch with pacman?
How do I force remove a package in Arch with pacman while other packages still depend upon it.
pacman -R perl-libwww
checking dependencies...
error: failed to prepare transaction (could…
xenoterracide
- 59,188
- 74
- 187
- 252
78
votes
11 answers
How can I reliably get the operating system's name?
Say I am logged into a remote system, how can I know what it's running? On most modern Linuxes (Linuces?), you have the lsb_release command:
$ lsb_release -ic
Distributor ID: LinuxMint
Codename: debian
Which as far as I can tell just…
terdon
- 242,166
78
votes
6 answers
Unzip file contents, but without creating archive folder
I have a file myarchive.zip that contains many directories, files, etc. Let's say this myarchive.zip file lives in a directory called "b". Well, when I use the "unzip myarchive.zip" command, the system creates a directory by default called…
ScoobaSteve
- 881
78
votes
3 answers
OpenSSH: How to end a match block
I'm using a Match block in OpenSSH's /etc/ssh/sshd_config (on debian) to restrict some users to SFTP:
# my stuff
Match group sftponly
X11Forwarding no
AllowTcpForwarding no
ForceCommand internal-sftp -u 0002
ChrootDirectory %h
As…
mreithub
- 3,583
78
votes
3 answers
Shebang line with `#!/usr/bin/env command --argument` fails on Linux
I've got a simple script:
#!/usr/bin/env ruby --verbose
# script.rb
puts "hi"
On my OSX box, it runs fine:
osx% ./script.rb
hi
However, on my linux box, it throws an error
linux% ./script.rb
/usr/bin/env: ruby --verbose: No such file or…
rampion
- 1,659
78
votes
3 answers
sshfs mount, sudo gets permission denied
I am using sshfs to mount a folder with some python projects over ssh to my ~/ directory.
$ mkdir -p ~/mount/my-projects
$ sshfs user@example.com:/home/user/my-projects ~/mount/my-projects
I can perform most commands as could be expected:
$ ls…
Uyghur Lives Matter
- 1,685