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Full Discussion: How does ||: evaluate?
Top Forums UNIX for Dummies Questions & Answers How does ||: evaluate? Post 302755085 by Don Cragun on Friday 11th of January 2013 06:48:01 PM
Old 01-11-2013
Quote:
Originally Posted by jim mcnamara
: evaluates in POSIX shells to the result of /usr/bin/true or true.

It is used like that to override a return status value that would affect subsequent processing.

For example, in Appworx (a batch control system) a false return code almost anywhere is detectable, so that if ||: were not there at the end of a line, appworx may see a false return and abort the job when the child process returns. Even though the job may have completed correctly.

Don't ask how, I'd have to guess.
A likely way to make this happen would be to use the command:
set -e
in a script that Appworx uses to start jobs, or for Appworx to use sh -e when it invokes a shell script.
 

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scrl(3XCURSES)						  X/Open Curses Library Functions					    scrl(3XCURSES)

NAME
scrl, scroll, wscrl - scroll a window SYNOPSIS
cc [ flag... ] file... -I /usr/xpg4/include -L /usr/xpg4/lib -R /usr/xpg4/lib -lcurses [ library... ] c89 [ flag... ] file... -lcurses [ library... ] #include <curses.h> int scrl(int n); int scroll(WINDOW *win); int wscrl(WINDOW *win, int n); PARAMETERS
n number and direction of lines to scroll win pointer to the window in which to scroll DESCRIPTION
The scroll() function scrolls the window win up one line. The current cursor position is not changed. The scrl() and wscrl() functions scroll the window stdscr or win up or down n lines, where n is a positive (scroll up) or negative (scroll down) integer. The scrollok(3XCURSES) function must be enabled for these functions to work. RETURN VALUES
On success, these functions return OK. Otherwise, they return ERR. ERRORS
None. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |Unsafe | +-----------------------------+-----------------------------+ SEE ALSO
clearok(3XCURSES), libcurses(3XCURSES), attributes(5), standards(5) SunOS 5.10 5 Jun 2002 scrl(3XCURSES)
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