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1500 questions
258
votes
6 answers
What does ` (backquote/backtick) mean in commands?
I came across the following command:
sudo chown `id -u` /somedir
and I wonder: what is the meaning of the ` symbol. I noticed for instance that while the command above works well, the one below does not:
sudo chown 'id -u' /somedir
gws
- 2,691
258
votes
4 answers
What does aux mean in `ps aux`?
ps aux seems to conveniently list all processes and their status and resource usage (Linux/BSD/MacOS), however I cannot comprehend the meaning of parameter aux using man ps.
What does aux mean?
Howard
- 5,209
258
votes
10 answers
Getting 256 colors to work in tmux
I have 256 colors working just fine in konsole,. I thought I'd give tmux a try because, unlike screen, it seems to support vi mode. However I find that the colors of my prompt show up and this is most likely because I have a 256 color mode prompt.…
xenoterracide
- 59,188
- 74
- 187
- 252
257
votes
6 answers
Can grep return true/false or are there alternative methods
As a part of this script, I need to be able to check if the first argument given matches the first word of file. If it does, exit with an error message; if it doesn't, append the arguments to the file. I understand how to write the if statement, but…
Lauren
- 2,635
256
votes
3 answers
Difference between 2>&-, 2>/dev/null, |&, &>/dev/null and >/dev/null 2>&1
Just looking for the difference between
2>&-
2>/dev/null
|&
&>/dev/null
>/dev/null 2>&1
and their portability with non-Bourne shells like tcsh, mksh, etc.
Det
- 2,682
256
votes
12 answers
How can I calculate the size of a directory?
How to know the size of a directory? Including subdirectories and files.
Juanjo Conti
- 2,723
254
votes
14 answers
Find the total size of certain files within a directory branch
Assume there's an image storage directory, say, ./photos/john_doe, within which there are multiple subdirectories, where many certain files reside (say, *.jpg). How can I calculate a summary size of those files below the john_doe branch?
I tried du…
mbaitoff
- 5,101
253
votes
4 answers
Why is FreeBSD deprecating GCC in favor of Clang/LLVM?
So I was surfing the net and stumbled upon this article. It basically states that FreeBSD, starting from Version 10 and above will deprecate GCC in favor of Clang/LLVM.
From what I have seen around the net so far, Clang/LLVM is a fairly ambitious…
NlightNFotis
- 7,575
253
votes
16 answers
Merging folders with mv?
If I use mv to move a folder called "folder" to a directory that already contains "folder" will they merge or will it be replaced?
Dominique
- 5,235
252
votes
14 answers
How to recursively find the amount stored in directory?
I know you are able to see the byte size of a file when you do a long listing with ll or ls -l. But I want to know how much storage is in a directory including the files within that directory and the subdirectories within there, etc. I don't want…
Rob Avery IV
- 3,155
252
votes
20 answers
How can I get distribution name and version number in a simple shell script?
I'm working on a simple bash script that should be able to run on Ubuntu and CentOS distributions (support for Debian and Fedora/RHEL would be a plus) and I need to know the name and version of the distribution the script is running (in order to…
Alix Axel
- 2,929
252
votes
5 answers
What is the 'working directory' when cron executes a job?
I have a script that works when I run it from the command line, but when I schedule it with cron I get errors that it cannot find files or commands. My question is twofold:
When I schedule a cron job using crontab -e, does it use my user ID as the…
ProfessionalAmateur
- 3,185
251
votes
2 answers
Unzipping a .gz file without removing the gzipped file
I have a file file.gz, when I try to unzip this file by using gunzip file.gz, it unzipped the file but only contains extracted and removes the file.gz file.
How can I unzip by keeping both unzipped file and zipped file?
jack
- 3,893
250
votes
9 answers
How to delete directories based on `find` output?
I issue the following command to find the .svn directories:
find . -name ".svn"
That gives me the following results:
./toto/.svn
./toto/titi/.svn
./toto/tata/.svn
How could I process all these lines with rm -fr in order to delete the directories…
Arnaud
- 2,611
250
votes
5 answers
How to rsync only new files
I am trying to set up rsync to synchronize my main web server to the remote server by adding newly generated file to the latter.
Here is the command that I use:
rsync -avh --update -e "ssh -i /path/to/thishost-rsync-key"…
supermario
- 3,269