University of California at Berkeley
           Department of Electrical Engineering & Computer Sciences
                     Instructional & Electronics Support Group

/share/b/pub/awk.help
								   June 2, 2002

'awk' is a standard UNIX command that can process lines of a text file.
It can identify individual fields, do arithmetic, do conditional ("if")
statements and pattern matching, and print out the results.

Each UNIX operating system has a version, typically located in /bin/awk.

The UNIX systems in EECS also have a shared version that is the GNU version,
called 'gawk'.  It can be accessed as either

  /usr/sww/bin/awk
  /usr/sww/bin/gawk

Type "man awk" for the local UNIX manual page.
Type "man -M /usr/sww/pkg/gawk*/man gawk" for the SWW UNIX manual page.
Type "awk --version" or "gawk --version" to see the version number.


Gawk 3.0.3 Arithmetic Bug
-------------------------
 We received this bug report about Gawk 3.0.3:

 > From das@HAL9000.wox.org  Sun May 26 03:30:19 2002
 > From: David Schultz <dschultz@uclink.Berkeley.EDU>

 > It appears that in GNU AWK 3.0.3, the last operand in a sequence of
 > arithmetic expressions is incorrectly rounded to 0 if its absolute
 > value is less than 1.  GNU AWK 3.0.6 has several annoying bugs, too,
 > but if you tell it to be compatable with bwk's AWK, they all go away. ;-)

 > Specifically, when you add 0.5 to a floating point number, the number
 > is sometimes unchanged.  GNU AWK 3.0.6 and The One True AWK behave
 > differently.  The workaround seems to be to say +1-0.5.
 
 > das@HAL9000:~> awk -V
 > awk version 20020210
 > das@HAL9000:~> awk 'BEGIN { i = 0.5 + 0.5; printf("%f\n", i); }'
 > 1.000000
 > 
 > das@HAL9000:~> gawk --version
 > GNU Awk 3.0.6
 > [snip GPL advertisement]
 > das@HAL9000:~> gawk 'BEGIN { i = 0.5 + 0.5; printf("%f\n", i); }'
 > 1.000000
 > 
 > pentagon ~/grading/sp02 > awk --version
 > GNU Awk 3.0.3
 > [snip GPL advertisement]
 > pentagon ~/grading/sp02 > awk 'BEGIN { i = 0.5 + 0.5; printf("%f\n", i); }'
 > 0.000000

 
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