I am taking a class in UNIX and have written a script that needs to countdown from a number that is read in from the keyboard to zero. If no number is given the start of the countdown should default to 10.
I can't get this to do the default
#! /bin/sh
echo Enter a number here to countdown... (2 Replies)
I am looking for a way to display on a single line, a running countdown for a given amount of time in a terminal using a bash script.
I am looking for this to use as part of a larger bash script that captures Video. The script sets up a bunch of parameters for DVgrab, and one of the parameters... (11 Replies)
Hi guys, I've found two nifty little scripts on these forums one which detects if the F5 key has been pressed:
#/bin/sh
_key()
{
local kp
ESC=$'\e'
_KEY=
read -d '' -sn1 _KEY
case $_KEY in
"$ESC")
while read -d '' -sn1 -t1 kp
do
_KEY=$_KEY$kp
... (0 Replies)
Hi all,
Does anyone know of any FUN countdown script that I can use for my script? At the moment, am just using sleep 10 or more and then print stuff into the screen to allow more time for the user to decide whether they want to continue running the script or abort?
Just thought of wanting... (3 Replies)
Hello, I have another problem with my script - I would like to have a countdown timer visible on the screen, and at the same time, I want te be able to do something else. And when the time runs out, I need to know about that inside the script somehow and do some action. I guess that would require 2... (3 Replies)
In the below bash when the perl is it possible to hide the commands from running on screen and display a process countdown?
For example, on the cygwin screen now the user sees each process in the command running as running protocol refGene, running protocol popfreq_all, etc... Could a... (0 Replies)
Hello. I am pretty new to unix and shell scripting and I was wondering if there might be a way to banner a countdown timer inside a script. We currently have an existing script that does a 2 minute sleep but thought it might be fun to actually make it banner a countdown timer until it is finished.... (3 Replies)
Discussion started by: thumbelina
3 Replies
LEARN ABOUT BSD
expr
EXPR(1) General Commands Manual EXPR(1)NAME
expr - evaluate arguments as an expression
SYNOPSIS
expr arg ...
DESCRIPTION
The arguments are taken as an expression. After evaluation, the result is written on the standard output. Each token of the expression is
a separate argument.
The operators and keywords are listed below. The list is in order of increasing precedence, with equal precedence operators grouped.
expr | expr
yields the first expr if it is neither null nor `0', otherwise yields the second expr.
expr & expr
yields the first expr if neither expr is null or `0', otherwise yields `0'.
expr relop expr
where relop is one of < <= = != >= >, yields `1' if the indicated comparison is true, `0' if false. The comparison is numeric if
both expr are integers, otherwise lexicographic.
expr + expr
expr - expr
addition or subtraction of the arguments.
expr * expr
expr / expr
expr % expr
multiplication, division, or remainder of the arguments.
expr : expr
The matching operator compares the string first argument with the regular expression second argument; regular expression syntax is
the same as that of ed(1). The (...) pattern symbols can be used to select a portion of the first argument. Otherwise, the
matching operator yields the number of characters matched (`0' on failure).
( expr )
parentheses for grouping.
Examples:
To add 1 to the Shell variable a:
a=`expr $a + 1`
To find the filename part (least significant part) of the pathname stored in variable a, which may or may not contain `/':
expr $a : '.*/(.*)' '|' $a
Note the quoted Shell metacharacters.
SEE ALSO sh(1), test(1)DIAGNOSTICS
Expr returns the following exit codes:
0 if the expression is neither null nor `0',
1 if the expression is null or `0',
2 for invalid expressions.
7th Edition April 29, 1985 EXPR(1)