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Full Discussion: How to print a string using printf?
Top Forums Shell Programming and Scripting How to print a string using printf? Post 302429420 by alister on Monday 14th of June 2010 11:29:55 AM
Old 06-14-2010
Quote:
Originally Posted by ygemici
or
Code:
# printf "$STR\n"
str1 str2 str3 str4

It's best not to use printf that way, since character sequences that are special to printf (format specifiers, escape sequences) will be misinterpreted and lead to mangled output. To print the value of a variable, it's best to use:
Code:
printf '%s\n' "$STR"


Example of how things would go wrong:
Code:
$ STR='%s'
$ # Incorrectly prints nothing but a newline
$ printf "$STR\n"

$ # Correctly prints out the value of $STR
$ printf "%s\n" "$STR"
%s

Using the printf(1) utility, this is nothing but a minor bug. Using the printf(3) function in the C standard library, this would be a HUGE security hole.

Regards,
Alister
 

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LEARN ABOUT MOJAVE

seq

SEQ(1)							    BSD General Commands Manual 						    SEQ(1)

NAME

     seq -- print sequences of numbers

SYNOPSIS

     seq [-w] [-f format] [-s string] [-t string] [first [incr]] last

DESCRIPTION

     The seq utility prints a sequence of numbers, one per line (default), from first (default 1), to near last as possible, in increments of incr
     (default 1).  When first is larger than last the default incr is -1.

     All numbers are interpreted as floating point.

     Normally integer values are printed as decimal integers.

     The seq utility accepts the following options:

     -f format	   Use a printf(3) style format to print each number.  Only the E, e, f, G, g, and % conversion characters are valid, along with
		   any optional flags and an optional numeric minimum field width or precision.  The format can contain character escape sequences
		   in backslash notation as defined in ANSI X3.159-1989 (``ANSI C89'').  The default is %g.

     -s string	   Use string to separate numbers.  The string can contain character escape sequences in backslash notation as defined in ANSI
		   X3.159-1989 (``ANSI C89'').	The default is 
.

     -t string	   Use string to terminate sequence of numbers.  The string can contain character escape sequences in backslash notation as
		   defined in ANSI X3.159-1989 (``ANSI C89'').	This option is useful when the default separator does not contain a 
.

     -w 	   Equalize the widths of all numbers by padding with zeros as necessary.  This option has no effect with the -f option.  If any
		   sequence numbers will be printed in exponential notation, the default conversion is changed to %e.

     The seq utility exits 0 on success and non-zero if an error occurs.

EXAMPLES

	   # seq 1 3
	   1
	   2
	   3

	   # seq 3 1
	   3
	   2
	   1

	   # seq -w 0 .05 .1
	   0.00
	   0.05
	   0.10

SEE ALSO

     jot(1), printf(1), printf(3)

HISTORY

     The seq command first appeared in Plan 9 from Bell Labs.  A seq command appeared in NetBSD 3.0, and ported to FreeBSD 9.0.  This command was
     based on the command of the same name in Plan 9 from Bell Labs and the GNU core utilities.  The GNU seq command first appeared in the 1.13
     shell utilities release.

BUGS

     The -w option does not handle the transition from pure floating point to exponent representation very well.  The seq command is not bug for
     bug compatible with the Plan 9 from Bell Labs or GNU versions of seq.

BSD
								 February 19, 2010							       BSD
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