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Full Discussion: $(< file ) and $( cat file )
Top Forums Shell Programming and Scripting $(< file ) and $( cat file ) Post 303012378 by Scrutinizer on Saturday 3rd of February 2018 01:12:05 AM
Old 02-03-2018
It does not work that way. $(<file) is a special case, which is a faster alternative to $(cat file). If you are using anything other than just a file, it becomes something else. $( ... ) is just command sustitution, so if we leave out that, it becomes:
Code:
< /dev/urandom tr -dc '[:alnum:],@#:!?+-' | head -c10

This is the same as tr -dc '[:alnum:],@#:!?+-' < /dev/urandom | head -c10
Code:
cat /dev/urandom -- tr -dc '[:alnum:],@#:!?+-' | head -c10

This is strange, it effectively just means cat /dev/urandom | head -c10
Code:
cat /dev/urandom | tr -dc '[:alnum:],@#:!?+-' | head -c10

This is the same as the first one with UUOC
Code:
< /dev/urandom | tr -dc '[:alnum:],@#:!?+-'  | head -c10

This is equivalent to :< /dev/urandom | tr -dc '[:alnum:],@#:!?+-' | head -c10, which is that same as :
: | tr -dc '[:alnum:],@#:!?+-' | head -c10
This User Gave Thanks to Scrutinizer For This Post:
ctsgnb
 

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LEARN ABOUT CENTOS

gldispatchcompute

GLDISPATCHCOMPUTE(3G)						   OpenGL Manual					     GLDISPATCHCOMPUTE(3G)

NAME

       glDispatchCompute - launch one or more compute work groups

C SPECIFICATION

       void glDispatchCompute(GLuint num_groups_x, GLuint num_groups_y, GLuint num_groups_z);

PARAMETERS

       num_groups_x
	   The number of work groups to be launched in the X dimension.

       num_groups_y
	   The number of work groups to be launched in the Y dimension.

       num_groups_z
	   The number of work groups to be launched in the Z dimension.

DESCRIPTION

       glDispatchCompute launches one or more compute work groups. Each work group is processed by the active program object for the compute
       shader stage. While the individual shader invocations within a work group are executed as a unit, work groups are executed completely
       independently and in unspecified order.	num_groups_x, num_groups_y and num_groups_z specify the number of local work groups that will be
       dispatched in the X, Y and Z dimensions, respectively.

ERRORS

       GL_INVALID_OPERATION is generated if there is no active program for the compute shader stage.

       GL_INVALID_VALUE is generated if any of num_groups_x, num_groups_y, or num_groups_z is greater than or equal to the maximum work-group
       count for the corresponding dimension.

ASSOCIATED GETS

       glGet() with argument GL_MAX_COMPUTE_WORK_GROUP_COUNT

SEE ALSO

       glDispatchComputeIndirect().

COPYRIGHT

       Copyright (C) 2012 Khronos Group. This material may be distributed subject to the terms and conditions set forth in the Open Publication
       License, v 1.0, 8 June 1999.  http://opencontent.org/openpub/.

AUTHORS

       opengl.org

opengl.org							    06/10/2014						     GLDISPATCHCOMPUTE(3G)
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