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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 ...
ManuelSchneid3r's user avatar
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=` ...
user avatar
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 ...
Mohammad's user avatar
  • 698
2 votes
2 answers
1k views

Why does the command echo `echo \\\z` output \z?

The command echo $(echo \\\z) is from the book , I don’t understand why it outputs \z I think it should output z
tmpbin's user avatar
  • 783
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 ...
Mark's user avatar
  • 1,189
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 ...
Rafaf Tahsin's user avatar
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 ...
csirac2's user avatar
  • 171
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 ...
Zeruno's user avatar
  • 153