Redirection???

[TheBigBasicQ]

Whats the difference between the '>' and '>>' operator and '<' and '<<'???

For example:

$ ls -l > myfile.txt

and

$ ls -l >> myfile.txt

Nobody is perfect =(
.
.
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I am nobody =D

 

[thedaver]

&quot;>&quot; overwrites an existing file or starts a new one if it does not exist.

&quot;>>&quot; appends to an existing file or starts a new one if it does not exist.

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[TheBigBasicQ]

Thanx.

Nobody is perfect =(
.
.
.
.
I am nobody =D

 

[danielhozac]

<

means to read input from the file.

<<

starts a here-document.

//Daniel

 

[TheBigBasicQ]

whats a here-document?

Nobody is perfect =(
.
.
.
.
I am nobody =D

 

[danielhozac]

It allows you to send input to a program from the command line, like this

cat > /etc/resolv.conf <<EOF
search domain.tld
nameserver 1.2.3.4
EOF

which I use in an initscript to recreate my

/etc/resolv.conf

after dhclient has done it's job.

//Daniel

 

[TheBigBasicQ]

hmm...ok so let me get this straight. < is used to redirect input to commands and << is redirect input to programs?

Nobody is perfect =(
.
.
.
.
I am nobody =D

 

[danielhozac]

<

is used to redirect input from a file.

<<

is used to redirect input from command line.

//Daniel

 

[flugh]

Here's a good link:

http://gd.tuwien.ac.at/linuxcommand.org/lts0060.html

Also, you may be thinking about the '2>&1' stuff you see. Check this link, down in section 3.4 &quot;Redirection&quot;:

http://www.ibiblio.org/gferg/ldp/practical_linux_guide/x80.html

----
JBR

 

[TheBigBasicQ]

Thanks those links were quite useful

Nobody is perfect =(
.
.
.
.
I am nobody =D