Questions tagged [linux]
A family of Unix-like operating systems using the Linux kernel. If your question is about a certain distribution only, use a more specific tag.
59,115
questions
1741
votes
10
answers
1.6m
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How can I sort the output of 'ls' by last modified date?
How can I sort the output of ls by last modified date?
nearly_lunchtime
1582
votes
6
answers
164k
views
How do I make a machine "blank screen" for a period of time (as a penalty) if certain noise levels are reached?
My kids (4 and 5) yell a lot when playing games on the computer. I found an effective cure for this. When I hear loud noises, I ssh into the game computer and do:
chvt 3; sleep 15; chvt 7
This ...
- 8,533
703
votes
12
answers
791k
views
View list of files in ZIP archive on Linux
How can I view the list of files in a ZIP archive without decompressing it?
- 7,583
646
votes
7
answers
926k
views
Permissions on private key in .ssh folder?
I changed my permissions in my .ssh folder and now when I use a piece of software that uses my private key, I have to type my password each time. What should my permissions be on my id_rsa file to ...
Jody G
644
votes
41
answers
559k
views
How to execute a command whenever a file changes?
I want a quick and simple way to execute a command whenever a file changes. I want something very simple, something I will leave running on a terminal and close it whenever I'm finished working with ...
- 13.3k
626
votes
5
answers
1.6m
views
How to find a directory on linux?
I have a VPS with Suse Linux 10.3.
I've logged in via SSH/putty and am trying to find where my web files are located.
Since I'm uploading via FTP in a directory called httpdocs, I assume that this ...
- 14.2k
603
votes
15
answers
356k
views
When reading a file with `less` or `more`, how can I get the content in colors?
When I read a file in Linux with the command less or more, how can I get the content in colors?
- 8,733
589
votes
12
answers
638k
views
Automatically answer 'Yes' when using apt-get install
Is there a way to make apt-get install automatically choose "yes" upon the Do you want to continue [y/N]? confirmation dialog?
- 6,887
579
votes
7
answers
772k
views
What is the "You have new mail" message in Linux/UNIX?
Sometimes, when I log into a box and 'su' to root, I get a cute little message saying I have mail (thank GOD it's not AOL).
Where is this mail?
What does it contain?
Who/What sent it?
How important ...
- 16.7k
574
votes
16
answers
489k
views
Reload a Linux user's group assignments without logging out
When assigning a user's secondary group list using:
# usermod -G <grouplist> <user>
is it possible to force this group assignment to take effect without logging out all running sessions?
...
- 6,232
572
votes
4
answers
225k
views
How to turn off word-wrap in less
Short version:
How can I make the less utility in Linux not wrap lines?
Long version:
Often I need to view huge CSV files using less with hundreds of columns. I frequently only care about the first ...
- 9,422
535
votes
6
answers
1.3m
views
How to decompress a .bz2 file
I have a file as: filename.bz2 I need to decompress.
I have tried the command: tar xvjf filename.tar.bz2, but it didn't work as the file is not a tar file.
How do I decompress this file?
- 5,495
523
votes
8
answers
899k
views
How to remove systemd services
If I install a new service then decide I don’t want that application anymore and delete it, the service is still listed in the output from systemctl as error.
Where is this coming from and how can I ...
- 5,331
507
votes
9
answers
57k
views
Did I just get hacked?
I am developing a consumer product, and it is supposed to be connected to the Internet, so as expected, it is connected to the Internet so that I can properly develop it.
I went away for an hour or ...
- 3,549
503
votes
18
answers
742k
views
How to clear the contents of a file from the command line?
I have a log file that has a bunch of stuff in it that I don't need anymore. I want to clear the contents.
I know how to print the contents to the screen:
cat file.log
I know how to edit the file, ...
- 15.1k
489
votes
7
answers
260k
views
What is the difference between executing a Bash script vs sourcing it?
What is the difference between executing a Bash script like A and sourcing a Bash script like B?
A
> ./myscript
B
> source myscript
- 5,091
487
votes
16
answers
1.2m
views
Test if a port on a remote system is reachable (without telnet)
In the old days, we used telnet to see if a port on a remote host was open: telnet hostname port would attempt to connect to any port on any host and give you access to the raw TCP stream.
These days,...
- 7,160
474
votes
18
answers
866k
views
How do I compare binary files in Linux?
I need to compare two binary files and get the output in the form
<fileoffset-hex> <file1-byte-hex> <file2-byte-hex>
for every different byte. So if file1.bin is
00 90 00 11
in ...
frustratedCmpNoLongerUser
451
votes
6
answers
601k
views
How can I resume a stopped job in Linux?
How can I resume a stopped job in Linux? I was using emacs and accidentally hit ctrl-z which blasted me back to the console. I can see it when I type 'jobs'
[*****]$ jobs
[1]+ Stopped ...
- 4,621
446
votes
7
answers
1.3m
views
How do I exit an SSH connection?
I’m connecting to a server via SSH to send a message to a socket server using a command like:
ssh 181.169.1.2 -p 5566
After the connection is established and I write the message and send it I can’...
- 4,571
431
votes
9
answers
896k
views
How to get the summarized sizes of directories and their subdirectories?
Let's say I want to get the size of each directory of a Linux file system. When I use ls -la I don't really get the summarized size of the folders.
If I use df I get the size of each mounted file ...
- 4,503
411
votes
11
answers
540k
views
How to check which apache modules are enabled/installed?
Which is the most elegant way to check which apache modules are enabled?
- 8,011
402
votes
21
answers
562k
views
How do I detach a process from Terminal, entirely?
I use Tilda (drop-down terminal) on Ubuntu as my "command central" - pretty much the way others might use GNOME Do, Quicksilver or Launchy.
However, I'm struggling with how to completely detach a ...
AnC
390
votes
4
answers
680k
views
Go back to previous directory in shell
Is there a way to go back to previous directory we were in using bash,tcsh without using pushd/popd ?
I'd like to type something like "back" and got returned to the previous directory I was in.
Edit:
...
- 6,029
372
votes
10
answers
383k
views
chown is not changing symbolic link
I'm trying to change the user/group of a symbolic link with the command:
$ chown -h myuser:mygroup mysymbolic/
But it's not changing. I'm logged in as root. The current user/group is set to root:...
rizidoro
358
votes
11
answers
778k
views
If I know the PID number of a process, how can I get its name?
If I have the PID number for a process (on a UNIX machine), how can I find out the name of its associated process?
What do I have to do?
- 7,201
352
votes
19
answers
321k
views
How to reliably keep an SSH tunnel open?
I use an SSH tunnel from work to go around various idotic firewalls (it's ok with my boss :)). The problem is, after a while the ssh connection usually hangs, and the tunnel is broken.
If I could at ...
- 6,324
338
votes
3
answers
479k
views
Linux unzip command: Option to force overwrite?
I am writing a shell script that unzips a ZIP file into an existing hierarchy of files, potentially overwriting some of the files.
The problem is that the unzip command asks for confirmation:
replace ...
- 11.1k
336
votes
9
answers
116k
views
How to append to a file as sudo?
I want to do:
echo "something" >> /etc/config_file
But, since only the root user has write permission to this file, I can't do that. But the following also doesn't work.
sudo echo "something" ...
- 7,437
314
votes
7
answers
368k
views
How do you redirect wget response to standard out?
I have a crontab that wgets a PHP page every five minutes (just to run some the PHP code), and I want to send the output of the request to standard out, while sending the normal wget output to /dev/...
- 3,475
304
votes
10
answers
785k
views
How can I list all IPs in the connected network, through Terminal preferably?
Using Ubuntu 10.10 command line, how can I list all IPs connected to my home network?
Ideally, it needs to be a CLI command as I will be running it from C++.
- 3,195
295
votes
5
answers
143k
views
What's the equivalent of Linux's updatedb command for the Mac?
If I want to use the locate command on a Linux machine, I usually run sudo updatedb first to update the database. I can run the locate command on OS X 10.5 but I can't find updatedb. What's the ...
- 4,397
289
votes
6
answers
323k
views
How to have Linux ls command show second in time stamp
Something annoying about ls -l command is it shows only hour and minute for a file(like 08:30). How can I see the second portion(like 08:30:44)?
man 1 ls and search for 'second' does not give any ...
- 6,014
285
votes
7
answers
310k
views
How do you gunzip a file and keep the .gz file?
The default behavior of gunzip is to delete the .gz file after it decompresses.
How do I prevent it from deleting the file??
If this functionality is not included then is there an alternative ...
- 2,953
280
votes
11
answers
757k
views
How do I get an entire directory in sftp?
I'm just learning to use sftp, and I want to copy a directory from the remote computer to my local computer. If I try
get [directory]
it gives me this error:
Cannot download non-regular file: /home/...
- 14.8k
278
votes
8
answers
912k
views
Get Last Modified Date of File in Linux
I'm new to Linux. I'm using the command-line. I'm trying to view the last modified date of a file. How do I do that in Linux from the Command Line?
- 2,919
276
votes
20
answers
341k
views
Unix/Linux find and sort by date modified
How can I do a simple find which would order the results by most recently modified?
Here is the current find I am using (I am doing a shell escape in PHP, so that is the reasoning for the variables):
...
Richard Easton
275
votes
9
answers
318k
views
In vim, how can I quickly switch between tabs?
In gnome-terminal, I can just press Alt + (1, 2, 3, etc.) to switch to specific tabs. I can also use Ctrl + (PgUp / PgDn) to cycle through tabs (admittedly less convenient, but it can be remapped).
...
- 14.8k
275
votes
3
answers
451k
views
ps aux output meaning
When typing the command ps aux, what does each column of the output mean? For example:
$ ps aux
timothy 29217 0.0 0.0 11916 4560 pts/21 S+ 08:15 0:00 pine
root 29505 0.0 0.0 38196 ...
- 17.3k
273
votes
3
answers
167k
views
Rename screen session
Is it possible to change the name of a GNU screen session? Say I called started it with "screen -S foo" and I want to rename it to bar.
- 3,084
272
votes
9
answers
677k
views
Get a list of Open Ports in Linux
I need a Linux command to list all free open ports for use in an application
lsof -i TCP| fgrep LISTEN
Does not seen to be helping as the Ports it lists are not necessarily free for use. How do I ...
- 2,831
269
votes
7
answers
276k
views
When should I use /dev/shm/ and when should I use /tmp/?
When should I use /dev/shm/ and when should I use /tmp/? Can I always rely on them both being there on UNIX?
- 5,208
266
votes
11
answers
633k
views
Is it possible to ping an address:port?
I am not into networking, and I have the following question related to the Linux ping command.
Can I only ping an address? For example:
miner@raspberrypi ~ $ ping onofri.org
PING onofri.org (67.222....
- 7,201
258
votes
5
answers
469k
views
Linux Bash Script, Single Command But Multiple Lines?
I have the following script I wrote by searching Google, and it backs up my Linux system to an archive:
#!/bin/bash
# init
DATE=$(date +20%y%m%d)
tar -cvpzf /share/Recovery/Snapshots/$HOSTNAME_$...
- 2,601
258
votes
8
answers
398k
views
Read the contents of a zipped file without extraction?
How can I read the contents of a particular file in an archive without extracting the .zip it is contained within? I'm using the Linux command line.
An earlier question asks about viewing the ...
- 2,581
253
votes
4
answers
460k
views
How to convert .ppk key to OpenSSH key under Linux?
I know that is possible to convert .ppk under puttygen in Windows, but how to do that on Linux? Is this possible ?
- 3,591
253
votes
8
answers
24k
views
What do the parentheses and number after a Unix command or C function mean?
I keep seeing parentheses and a number after a command in Unix or Linux or C function.
For example: man(8), ftok(2), mount(8), etc.
What do these mean? I see them in man too.
- 3,059
251
votes
35
answers
296k
views
Is there a way to display a countdown or stopwatch timer in a terminal?
How can I display a real-time countdown timer on the Linux terminal? Is there an existing app or, even better, a one liner to do this?
- 2,751
249
votes
10
answers
284k
views
How can I avoid SSH's host verification for known hosts?
I get the following prompt everytime I try to connect a server using SSH. I type "yes", but is there a way to aovid this?
The authenticity of host '111.222.333.444 (111.222.333.444)' can't be ...
- 2,793
249
votes
11
answers
371k
views
What to do when Ctrl + C can't kill a process?
Ctrl + C doesn't always work to kill the current process (for instance, if that process is busy in certain network operations). In that case, you just see "^C" by your cursor and can't do ...
- 2,601