Use execve to write a
The 1s program gets the width of the screen from the COLUMNS environment variable. If COLUMNS is Unset, then 1s assumes that the screen is 80 columns wide. Thus, you can check your handling of the environment variables by setting the COLUMNS environment to something less than 80:
linux> setenv COLUMNS
linux> ./my1s
.
. //Output is 40 columns wide
.
linux> unsetenv COLUMNS
linux> ./my1s
.
//Output is now 80 columns wide
.
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