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1500 questions
490
votes
19 answers
Get exit status of process that's piped to another
I have two processes foo and bar, connected with a pipe:
$ foo | bar
bar always exits 0; I'm interested in the exit code of foo. Is there any way to get at it?
Michael Mrozek
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- 38
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483
votes
10 answers
How do I delete a file whose name begins with "-" (hyphen a.k.a. dash or minus)?
How do you remove a file whose filename begins with a dash (hyphen or minus) -? I'm ssh'd into a remote OSX server and I have this file in my directory:
tohru:~ $ ls -l
total 8
-rw-r--r-- 1 me staff 1352 Aug 18 14:33 --help
...
How in the…
Astra
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478
votes
5 answers
Why not use "which"? What to use then?
When looking for the path to an executable or checking what would happen if you enter a command name in a Unix shell, there's a plethora of different utilities (which, type, command, whence, where, whereis, whatis, hash, etc).
We often hear that…
Stéphane Chazelas
- 522,931
- 91
- 1,010
- 1,501
478
votes
5 answers
How does reverse SSH tunneling work?
As I understand this, firewalls (assuming default settings) deny all incoming traffic that has no prior corresponding outgoing traffic.
Based on Reversing an ssh connection and SSH Tunneling Made Easy, reverse SSH tunneling can be used to get around…
Ali
- 5,261
- 5
- 20
- 18
474
votes
6 answers
What does "LC_ALL=C" do?
What does the C value for LC_ALL do in Unix-like systems?
I know that it forces the same locale for all aspects but what does C do?
jcubic
- 9,612
- 16
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- 75
468
votes
11 answers
How do I use pushd and popd commands?
What are the practical uses of both pushd and popd when there is an advantage of using these two commands over cd and cd -?
EDIT: I'm looking for some practical examples of uses for both of these commands or reasons for keeping stack with…
syntagma
- 12,091
- 21
- 57
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461
votes
5 answers
What is the difference between curl and wget?
I am keen to know the difference between curl and wget. Both are used to get files and documents but what the key difference between them.
Why are there two different programs?
lakshmen
- 6,071
- 5
- 17
- 9
455
votes
3 answers
What should/shouldn't go in .zshenv, .zshrc, .zlogin, .zprofile, .zlogout?
I'm looking for guidelines on what one should and should not include in the various startup files for zsh.
I understand the order of sourcing of these files, and the conditions under which they are sourced, but it is still not clear to me what…
kjo
- 14,779
- 25
- 69
- 109
451
votes
11 answers
How can I run a command which will survive terminal close?
Sometimes I want to start a process and forget about it. If I start it from the command line, like this:
redshift
I can't close the terminal, or it will kill the process. Can I run a command in such a way that I can close the terminal without…
Matthew
- 5,417
- 4
- 19
- 11
447
votes
6 answers
Delete from cursor to end of line in `vi`
I know I've probably looked over this a million times in all the vi documents I've read, but I can't seem to find the delete from cursor to end of line command.
Falmarri
- 12,897
- 17
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443
votes
2 answers
Using 'sed' to find and replace
I know this question has probably been answered before. I have seen many threads about this in various places, but the answers are usually hard to extract for me. I am looking for help with an example usage of the 'sed' command.
Say I wanted to…
roo
- 4,591
- 4
- 12
- 7
434
votes
9 answers
When should I not kill -9 a process?
I am always very hesitant to run kill -9, but I see other admins do it almost routinely.
I figure there is probably a sensible middle ground, so:
When and why should kill -9 be used? When and why not?
What should be tried before doing it?
What kind…
Mikel
- 56,387
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431
votes
18 answers
How can I use sed to replace a multi-line string?
I've noticed that, if I add \n to a pattern for substituting using sed, it does not match. Example:
$ cat > alpha.txt
This is
a test
Please do not
be alarmed
$ sed -i'.original' 's/a test\nPlease do not/not a test\nBe/' alpha.txt
$ diff…
Belmin Fernandez
- 9,347
- 15
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430
votes
3 answers
refresh changed content of file opened in vi(m)
I have a config-file that I keep open in vim, but that sometimes gets changed on disk, without these changes being reflected on the terminal. Can I refresh the content on the screen without closing and re-opening the file? If so, how?
twan163
- 5,590
- 4
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- 17
429
votes
4 answers
find's "-exec rm {} \;" vs "-delete"
I'm trying to understand the difference between these two commands:
sudo find / -name .DS_Store -delete
and
sudo find / -name ".DS_Store" -exec rm {} \;
I noticed that the -exec ... {} method is preferred. Why? Which one is safer/faster/better?…
Onion
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