Hi all,
I have been writing a script to automate some work for myself and have come accross a problem. I cannot understand why it doesn't work, but then I am new to both Unix and Korn shell hacking! Here is the problem:
I want to interogate a file for a number and store that number in... (6 Replies)
I use a tcsh and I need to monitor a file that its constantly updating.
In the past I remember using less -(an option) fileName.
This option told less to keep listening to this file and output the any changes.
What is this option??? I think I read the man page for less like 5 times and I... (3 Replies)
Hi, I've created a script in csh that takes a file and checks it for mispelled words. Im almost done but I need to do two more things but I need help.
First, when displaying an incorrect word to the user, I need to show the line of the input file that contains the word.
Second,if the user... (0 Replies)
Hello guys I am trying to learn perl and have a simple calculator I am trying to run but I get error runaway multi-line. Can someone point this rookie in the right direction.
###
print 'Welcome to the Calculator';
print 'Would you like to enter the calculator? Please Type y or n';
$run =... (9 Replies)
Hi everyone,
Is there anywhere I can find a complete table of all characters that must be escaped by the various UNIX shells and scripting languages?
It seems every command/shell/scripting language has different rules about what characters must be escaped.
I do a lot of searching and... (3 Replies)
normally, i hate asking someone to do my homework for me but am getting desperate right now.
i have a project about consumer producer problem. the deadline is tonight at 23:55. but i havent gotten it working yet. i just COULDNT get it to work right yet.
the problem is as follows: the C - program... (0 Replies)
Use and complete the template provided. The entire template must be completed. If you don't, your post may be deleted!
1. The problem statement, all variables and given/known data:
normally, i hate asking someone to do my homework for me but am getting desperate right now.
i have a project... (1 Reply)
I bought a server cabinet recently and the person who sold it to me included some strange nuts. Can anyone tell me what they are called? I need to buy more. Below is the image of them.
Thank you!
http://s23.postimg.org/50fx2ge6j/image.jpg
http://s23.postimg.org/o498isr0r/image.jpg
... (1 Reply)
Discussion started by: danijeljames
1 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)