CODEWITHSUNDEEP
linuxshellunixterminal
ojhawkins
ojhawkins

Reputation: 3288

Copy a variable in shell script (Linux)

How can I copy a variable to another variable in a shell script?

Assuming the user has passed in $1, how can its value be copied to another variable?

I assume it would look something like this...

cp $1 $2

echo "Copied value: $2"

Upvotes: 3

Views: 12971

Answers (5)

Marty McGowan
Marty McGowan

Reputation: 366

i've found set -- to be a very useful command to set the positional parameters. e.g. in the example you gave, and well answered:

cp file1 file2

copies "file1" to "file2". frequently when i work with a few files, I'll do this instead:

set -- file1 file2
cp $1 $2

and if you want to reverse the names in the variables:

set -- $2 $1        # puts the current "$2" value in "$1", and vice versa, then
cp $1 $2            # copies what was   file2   contents back to file1.

this without using any "named" variables, which you've already seen. my more common use is like:

set -- ${1%.txt}    # strips a ".txt" suffix 
set -- $1 $1.out $1.err   # sets 2nd to <whatever>.out and 3rd to <whatever>.err, so
cmd $1.txt > $2 2>$3      # puts stdout in  ...out  and stderr in ...err

v

Upvotes: 0

Syntax
Syntax

Reputation: 169

You are using cp which is for copying files.

Just use

v=$1

and echo it:

echo "Copied Variable: $v"

Upvotes: 0

user2045557
user2045557

Reputation: 

val=$1  
echo "Copied Value : $val"

Upvotes: 0

hek2mgl
hek2mgl

Reputation: 158070

Firstly cp is for copying files and directories only (as the man page states)

Secondly, it is not possible to assign to an argument variable ($0..$1..$n). They are meant to be read only.

You can do this instead:

input2=$1

It will copy the value of $1 to a new variable called $input2

Upvotes: 1

fedorqui
fedorqui

Reputation: 289955

Note that cp is used to copy files and directories. To define variables, you just have to use the following syntax:

v=$1

Example

$ cat a
echo "var v=$v"
v=$1
echo "var v=$v"
$ ./a 23         <---- we execute the script
var v=           <---- the value is not set
var v=23         <---- the value is already set

Upvotes: 3

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