Thread: SC (System Command) using an escape character (@) in a macro does not work

Started: 2007-03-14 21:48:14
Last activity: 2007-03-16 01:25:31
Topics: SAC Help


I am using some SAC applications that have been developed elsewhere and
work on SunOS Unix. I am running sac2000 on SunOS 5.8.

I have a problem when a macro issues a "system command" (sc) that needs an
escape character before a character that would otherwise be interpreted by
SAC. The command that is passed to Unix does have the escape character
removed but it is not interpreted correctly by Unix.

For example, the following command returns an syntax error for the awk
portion of it:

sc grep 6.0_8.0 %file_vel% | awk '{print "setbb v0 " @$3}' > junk; m
junk

As a simpler test is issued the following set of commands from within SAC:

sc grep 6.0_8.0 %file_vel% > xx
sc cat xx
sc set info = `cat xx`
sc echo @$info

The 2nd line, the "cat xx" does print the contents of the file xx correctly
but the 4th line only prints a blank line, not the contents of the variable
info. When I do the same thing outside of SAC at the system prompt, the
variable info contains the contents of the file xx.

Any guidance would be appreciated.

Nancy
-----------------------------------
Nancy F. Collins
URS Corporation
566 El Dorado Street, Suite 200
Pasadena, CA 91101
(626) 449-7650; FAX (626) 449-3536


  • Nancy

    the first example works for me, too. The second example does not work
    because (I think; sac-devs can correct me if I am wrong)

    1. Each sc command runs in its own shell; i.e. there is no way you can
    recover shell variables set in one run of sc in the next sc command as
    the corresponding shell would have been closed.

    2. sh rather than csh is used for execution. In sh, variables which are
    not set expand to nothing

    As a workaround you can use this somewhat awkward construction:

    SAC> sc echo 'set info = `cat xx` ; echo x @$info x' | csh

    I suspect event the following would work bypasssing the need for a temp file


    SAC> sc echo 'set info = `grep 6.0_8.0 %file_vel%` ; echo x @$info x' | csh

    which explicitly uses csh by piping into it.

    Regards
    Frederik


    Nancy_Collins<at>urscorp.com wrote:
    I am using some SAC applications that have been developed elsewhere and
    work on SunOS Unix. I am running sac2000 on SunOS 5.8.

    I have a problem when a macro issues a "system command" (sc) that needs
    an escape character before a character that would otherwise be
    interpreted by SAC. The command that is passed to Unix does have the
    escape character removed but it is not interpreted correctly by Unix.

    For example, the following command returns an syntax error for the awk
    portion of it:

    *sc grep 6.0_8.0 %file_vel% | awk '{print "setbb v0 " @$3}' > junk; m junk*

    As a simpler test is issued the following set of commands from within SAC:

    *sc grep 6.0_8.0 %file_vel%** > xx*
    * sc cat xx*
    * sc set info = `cat xx`*
    * sc echo @$info*

    The 2nd line, the "cat xx" does print the contents of the file xx
    correctly but the 4th line only prints a blank line, not the contents of
    the variable info. When I do the same thing outside of SAC at the system
    prompt, the variable info contains the contents of the file xx.

    Any guidance would be appreciated.

    Nancy
    -----------------------------------
    Nancy F. Collins
    URS Corporation
    566 El Dorado Street, Suite 200
    Pasadena, CA 91101
    (626) 449-7650; FAX (626) 449-3536



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  • Nancy,

    Your first example works fine for me.
    So maybe your SAC or awk version is outdated? I'm using sac 100.1 and gawk
    3.5.1 on Linux..

    However, the second example is not working for some reason.

    Good luck,
    Andreas

    On 3/15/07, Nancy_Collins<at>urscorp.com <Nancy_Collins<at>urscorp.com> wrote:

    *sc grep 6.0_8.0 %file_vel% | awk '{print "setbb v0 " @$3}' > junk; m junk
    *

    As a simpler test is issued the following set of commands from within SAC:

    *sc grep 6.0_8.0 %file_vel%** > xx*
    * sc cat xx*
    * sc set info = `cat xx`*
    * sc echo @$info*

    The 2nd line, the "cat xx" does print the contents of the file xx
    correctly but the 4th line only prints a blank line, not the contents of the
    variable info.
    http://www.iris.washington.edu/mailman/listinfo/sac-help



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