All Questions
26
questions
81
votes
4
answers
205k
views
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 ...
- 1,189
34
votes
4
answers
168k
views
What is the difference between echo `date`, echo "`date`", and echo '`date`'?
What is the difference between these three commands?
echo `date`
echo "`date`"
echo '`date`'
I am confused on what the differences actually are. I think that when the ' are around it means that it ...
- 3,639
33
votes
5
answers
145k
views
Why is echo ignoring my quote characters?
The echo command isn't including the complete text that I give it. For example, if I do:
$ echo ' echo PARAM=` grep $ARG /var/tmp/setfile | awk '{print $2}' ` '
It outputs:
echo PARAM=` ...
Diana
15
votes
6
answers
9k
views
Why there is such a difference in execution time of echo and cat?
Answering this question caused me to ask another question:
I thought the following scripts do the same thing and the second one should be much faster, because the first one uses cat that needs to open ...
- 698
14
votes
2
answers
12k
views
Is it dangerous to run echo without quotes?
I've seen couple of similar topics, but they are referring to not quoting variables, which I know could lead to unwanted results.
I saw this code and was wondering would if it be possible to inject ...
- 251
14
votes
2
answers
8k
views
Quoted vs unquoted string expansion
for i in $(xrandr); do echo "$i" ; done
for i in "$(xrandr)"; do echo "$i"; done
for i in "$(xrandr)"; do echo $i; done
I understand why 1 differs from 2. But why does 3 give a different output from ...
- 4,406
13
votes
2
answers
3k
views
What is the difference between single quoted $'string' and double quoted $"string" in bash?
I was trying to execute new line using echo and tried following two commands:
First command:
echo $'Hello World\nThis is a new line'
Response:
Hello World
This is a new line
Second command:
echo ...
- 281
9
votes
7
answers
19k
views
echo \\* - bash backslash escape behavior, is it evaluated backwards?
So in bash,
When I do
echo \*
*
This seems right, as * is escaped and taken literally.
But I can't understand that,
when I do
echo \\*
\*
I thought the first backslash escaped the second one ...
- 213
8
votes
3
answers
89k
views
echo variable with content from command substitution
I wrote a very basic script of command substitution which is below:
#!/bin/bash
files=$(ls *.fastq);
echo $files
The directory contains bunch of .fastq file and I just want to use echo command to ...
- 2,559
7
votes
2
answers
887
views
Why does dash's echo expand \\\\ differently to bash's echo?
I have a little open source project that for various reasons I've tried to write in reasonably portable shell script. Its automated integration tests check that hostile characters in path expressions ...
- 171
6
votes
2
answers
8k
views
How do I echo an expression with both single and double quotes?
I have tried many things, but I'm new to the shell. Is it possible to have both double and single quotes within an echo?
I want to generate echo "scan 'LPV',{FILTER => "(PrefixFilter ('MP1-Eq1')"}"...
- 771
6
votes
2
answers
3k
views
What are the effects of double quotes in echo statements? [closed]
When writing a Bash script that contains messages for the user, I can write
echo Processing files...
or
echo "Processing files..."
In this and many other cases, the output will be the same....
- 1,471
5
votes
4
answers
3k
views
Echoing something with multiple quotes and key characters (&, $, !, etc.)
Let's say you have to echo this into a file:
RZW"a4k6[)b!^"%*X6Evf
How do you do it?
My actual "line" to echo is a 2048 characters line.
- 105
5
votes
3
answers
17k
views
Echo new line and string beginning \t
Sure, echo -e can be used so that \n is understood as a new line. The problem is when I want to echo something beginning with \t e.g. "\test".
So let's say I want to perform echo -e "test\n\\test". I ...
- 153
5
votes
2
answers
633
views
Why am I observing different behaviour of echo?
I observed the below behavior of echo
#!/bin/bash
x=" hello"
echo $x
echo "$x"
Now when I run the above code I get
ronnie@ronnie:~$ bash test.sh
hello
hello
ronnie@ronnie:~$
So, can someone ...
- 901