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More efficient way to print variable values?

 
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Top Forums UNIX for Dummies Questions & Answers More efficient way to print variable values?
# 1  
Old 08-30-2014
More efficient way to print variable values?
Hello,

Through the process of a executing a shell script, I extract the values for a number of variables (arbitrarily declared as a through i) and towards the end I print them out like shown below:
Code:
#!bin/sh

# bits of code to get values for the variables
......
......

# print the values
printf "$a\t$b\t$c\t$d\t$e\t$f\t$g\t$h\t$i\n" >>  Values.out

exit 0

Is there a more efficient way to put the values into an array and print them out with specified delimiters?

Thank you for your input!

~Guss
Moderator's Comments:
Mod Comment Please use CODE tags (not ICODE tags) when posting multi-line input, output, and code segments.
Last edited by Don Cragun; 08-30-2014 at 04:36 PM.. Reason: Chane ICODE tags to CODE tags; remove COLOR tags.
# 2  
Old 08-30-2014
If any of your variables could ever contain a percent sign or a backslash character, you should not put the values themselves in your format string. A much safer way would be:
Code:
printf '%s\t' "$a" "$b" "$c" "$d" "$e" "$g" "$h"
print '%s\n' "$i

or:
Code:
printf '%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s\n' "$a" "$b" "$c" "$d" "$e" "$g" "$h" "$i"

or, if you had an array containing 8 elements:
Code:
printf '%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s\n' "${array[@]}"

If you had the variables in an array and wanted to print each value on a separate line, you could use:
Code:
printf '%s\n' "${array[@]}"

no matter how many elements are in the array.
# 3  
Old 08-31-2014
${array[@]} expands each element to a separate word. printf will implicitly loop if more arguments are given than format specifiers.

${array[*]} expands to a single word with values separated by the first character of IFS
IFS is normally $' \t\n' you can either change the order permanently or switch back and forth by saving it, use a subshell or a function and local variable, ...

subshell example
Code:
$ ( IFS=:; printf '%s\n' "${a[*]}"; ); printf '%q\n' "$IFS"
1:2:3:4:5:6:7:8:9:10
$' \t\n'

function example
Code:
$ printvalues() { local IFS=:; printf "%s\n" "$*"; }; printvalues "${a[@]}"; printf '%q\n' "$IFS"
1:2:3:4:5:6:7:8:9:10
$' \t\n'

# 4  
Old 08-31-2014
Setting IFS before read works fine because that command uses the variable..

Setting IFS before printf won't do because the shell expands the array before the command is executed.
This User Gave Thanks to neutronscott For This Post:
Don Cragun
# 5  
Old 08-31-2014
Quote:
Originally Posted by neutronscott
Setting IFS before read works fine because that command uses the variable..

Setting IFS before printf won't do because the shell expands the array before the command is executed.
Ouch. Yes. Sorry.
I need more sleep.
 
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