Visit Our UNIX and Linux User Community

With that logic this echoes "echo". Question about echo!

Thread Tools Search this Thread
Top Forums Shell Programming and Scripting With that logic this echoes "echo". Question about echo!
# 1  
Old 11-11-2010
Hammer & Screwdriver With that logic this echoes "echo". Question about echo!

echo `echo `

doesn't echoes anything. And it's logic. But
echo `echo `echo ` `

does echoes "echo". What's the logic of it? the `echo `echo ` inside of the whole (first) echo, echoes nothing, so the first echo have to echo nothing but echoes "echo"

(too much echoing :P)Smilie
# 2  
Old 11-11-2010
That is because backticks have to be escaped if you nest them:
echo `echo \`echo \` `

You do not need to with the more modern $(..) command substitution construct:
 echo $(echo $(echo))

# 3  
Old 11-11-2010
Thx, it seems interesting Smilie

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. UNIX for Beginners Questions & Answers

Basic question on "echo"

what happens when I echo asterisk? Please don't hijack other peoples' thread; post our own new one as required by forum rules! (5 Replies)
Discussion started by: ithenr00
5 Replies

2. UNIX for Dummies Questions & Answers

Difference between echo `ls -l` and echo "`ls -l`" ?

Hi guys, Been messing around with shell programming for a couple of days and I found something that was pretty odd in the behavior of the echo command. Below is an example-: When I type the following in my /home directory from my lxterminal in Debian-: echo "`ls -l`" I get the... (2 Replies)
Discussion started by: sreyan32
2 Replies

3. Shell Programming and Scripting

tcsh - understanding difference between "echo string" and "echo string > /dev/stdout"

I came across and unexpected behavior with redirections in tcsh. I know, csh is not best for redirections, but I'd like to understand what is happening here. I have following script (called out_to_streams.csh): #!/bin/tcsh -f echo Redirected to STDOUT > /dev/stdout echo Redirected to... (2 Replies)
Discussion started by: marcink
2 Replies

4. AIX

echo $varibla | mail -s "subject" "" not ruuning as expected

Hi Folks, As per the subject, the following command is not working as expected. echo $variable | mail -s "subject" "" Could anyone figure it out whats wrong with this. I am using AIX box. Regards, (2 Replies)
Discussion started by: gjarms
2 Replies

5. Shell Programming and Scripting

cmd || echo "something" - doesn't exit uppon error

Hi guys, I have a shell script where I have the following: for i in ad0 ad1 do gpart create -s gpt $i || echo "Cannot create GPT partition on "$i". Exiting ..." gpart add -s 128 -t freebsd-boot $i || echo "Cannot add freebsd-boot partition on "$i". Exiting ..." gpart add -s 4G -t... (2 Replies)
Discussion started by: da1
2 Replies

6. Shell Programming and Scripting

"Simple" echo/reading variable question...

Hello, I have a simple(I think) question! Although simple, I have been unable to resolve it, so I hope someone can help! OK, here it is: 1)I have an awk script that prints something, such as: awk '{print $2}' a > x so x might hold the value of say '10' 2)Now, I just want to check to see if... (4 Replies)
Discussion started by: astropi
4 Replies

7. Shell Programming and Scripting

ksh script that echo " please insert your name " and store the output to a login.log file.

Hello All Nice to meet you all here in this forum, it's my 1rst time here i'm asking about a little issue that i face i added a ksh script that echo " please insert your name " and store the output to a login.log file. the script is working fine with normal telnet but Xstart is not working... (8 Replies)
Discussion started by: islam.said
8 Replies

8. Shell Programming and Scripting

Difference between using "echo" builtin and /bin/echo

So in my shell i execute: { while true; do echo string; sleep 1; done } | read line This waits one second and returns. But { while true; do /bin/echo string; sleep 1; done } | read line continues to run, and doesn't stop until i kill it explicitly. I have tried this in bash as well as zsh,... (2 Replies)
Discussion started by: ulidtko
2 Replies

9. Shell Programming and Scripting

"sed" to check file size & echo " " to destination file

Hi, I've modified the syslogd source to include a thread that will keep track of a timer(or a timer thread). My intention is to check the file size of /var/log/messages in every one minute & if the size is more than 128KB, do a echo " " > /var/log/messages, so that the file size will be set... (7 Replies)
Discussion started by: jockey007
7 Replies

10. Solaris

question for "echo"

what is the mean: echo -n "^0;!*^G" thanks (3 Replies)
Discussion started by: chris_chang
3 Replies

Featured Tech Videos