10 More Discussions You Might Find Interesting
1. Shell Programming and Scripting
HI there
I am trying to understand Shell scripting to create my own, I am attempting a few examples can anyone tell me what this means?n=$( expr $n + 1)Tried looking on the internet, but just cannot find its anywhere :( .Help please (4 Replies)
Discussion started by: steve2015
4 Replies
2. Shell Programming and Scripting
Hi
I have bellow script:
t1=`cat node1.txt | grep thread1 | cut -f2 -d '-'`
t2=`cat node2.txt | grep thread2 | cut -f2 -d '-'`
t3=`cat node1_rcat.txt | grep thread1 | cut -f2 -d '-'`
t4=`cat node2_rcat.txt | grep thread2 | cut -f2 -d '-'`
if ]; then
echo "no restore" >> log.log... (6 Replies)
Discussion started by: primo102
6 Replies
3. Shell Programming and Scripting
Hi All,
I'm writing a shell script in KSH, where I want to store the filename, total record count and actual record count of all the source files. The source files reside in 4 different sub-folders under the same root folder.
Below is code:
#!/usr/bin/ksh... (6 Replies)
Discussion started by: jagari
6 Replies
4. UNIX for Dummies Questions & Answers
i have been told that 'let' is faster than 'expr' in terms of performance.
Is this correct? if yes, why is it so?
i am not able to see any performance difference in small arithmetic operations.
Thanks (3 Replies)
Discussion started by: pandeesh
3 Replies
5. UNIX for Dummies Questions & Answers
Hey there
i want to subtract the content from $b from $a. Each variable has got 18 values (normal numbers from 0 - 99).
How can i subtract them? I know i have to use the expr command, this is what i have till now:
a=`cat Tabelle.dat | awk {'print $4'} | awk -F: {'print $1'}`
b=`cat... (1 Reply)
Discussion started by: Mad van Bert
1 Replies
6. Shell Programming and Scripting
$ cat > mtable
#!/bin/sh
#
#Script to test for loop
#
#
if
then
echo "Error - Number missing form command line argument"
echo "Syntax : $0 number"
echo "Use to print multiplication table for given number"
exit 1
fi
n=$1
for i in 1 2 3 4 5 6 7 8 9 10
do
echo "$n * $i = `expr $i \*... (1 Reply)
Discussion started by: jackel7777
1 Replies
7. Shell Programming and Scripting
What is the difference between test expr VS .
For example :
if test 5 -eq 6
echo "Wrong"
and
if
echo "Wrong"
bot will give the same output as Wrong.
Now, what is the difference between these two? though they are producing the same result why we need two?
Any answer will be... (2 Replies)
Discussion started by: ashok.g
2 Replies
8. Red Hat
i am new to shell programming, currently using redhat linux of version
2.4.20-8.
i have problem in executing expr command in the following shell script
$ x=5
$ x='expr $x + 1'
$ echo $x
the output is displaying always
expr $x + 1
Pls guide me for the above query (3 Replies)
Discussion started by: saikumarm80
3 Replies
9. UNIX for Dummies Questions & Answers
I am running the following
Y=05
Y=`expr $X - 1`
and I getting a result of 4. Does anyone know if there is a way to make the result 04 instead of 4? (3 Replies)
Discussion started by: low90s
3 Replies
10. UNIX for Dummies Questions & Answers
Hello!
I want to evaluate some mathematical expressions in a script and I try to use 'expr' command.
Unfortunatally, when I have, for example,
expr 8.2 + 6
the result is 'expr: non-numeric argument'
Why ?
I work on SunOs 5.7.
Thanks in advance
Nathe (5 Replies)
Discussion started by: Nathe
5 Replies
expr(1B) SunOS/BSD Compatibility Package Commands expr(1B)
NAME
expr - evaluate arguments as a logical, arithmetic, or string expression
SYNOPSIS
/usr/ucb/expr argument...
DESCRIPTION
The expr utility evaluates expressions as specified by its arguments. After evaluation, the result is written on the standard output. Each
token of the expression is a separate argument, so terms of the expression must be separated by blanks. Characters special to the shell
must be escaped. Note: 0 is returned to indicate a zero value, rather than the null string. Strings containing blanks or other special
characters should be quoted. Integer-valued arguments may be preceded by a unary minus sign. Internally, integers are treated as 32-bit,
two's-complement numbers.
The operators and keywords are listed below. Characters that need to be escaped are preceded by `'. The list is in order of increasing
precedence, with equal precedence operators grouped within {} symbols.
expr | expr
Returns the evaluation of the first expr if it is neither NULL nor 0; otherwise, returns the evaluation of the second expr if it is not
NULL; otherwise, 0.
expr & expr
Returns the first expr if neither expr is NULL or 0, otherwise returns 0.
expr { =, , , <, <=, != } expr
Returns the result of an integer comparison if both arguments are integers, otherwise returns the result of a lexical comparison.
expr { +, - } expr
Addition or subtraction of integer-valued arguments.
expr { , /, % } expr
Multiplication, division, or remainder of the integer-valued arguments.
string : regular-expression
match string regular-expression
The two forms of the matching operator above are synonymous. The matching operators : and match compare the first argument with the
second argument which must be a regular expression. Regular expression syntax is the same as that of regexp(5), except that all pat-
terns are "anchored" (treated as if they begin with ^) and therefore ^ is not a special character, in that context. Normally, the
matching operator returns the number of characters matched (0 on failure). Alternatively, the ... pattern symbols can be used to
return a portion of the first argument.
substr string integer-1 integer-2
Extracts the substring of string starting at position integer-1 and of length integer-2 characters. If integer-1 has a value greater
than the length of string, expr returns a null string. If you try to extract more characters than there are in string, expr returns all
the remaining characters from string. Beware of using negative values for either integer-1 or integer-2 as expr tends to run forever
in these cases.
index string character-list
Reports the first position in string at which any one of the characters in character-list matches a character in string.
length string
Returns the length (that is, the number of characters) of string.
( expr )
Parentheses may be used for grouping.
EXAMPLES
Example 1 Adding an integer to a shell variable
Add 1 to the shell variable a.
a='expr $a + 1'
Example 2 Returning a path name segment
Return the last segment of a path name (that is, the filename part). Watch out for / alone as an argument: expr will take it as the divi-
sion operator (see BUGS below).
# 'For $a equal to either "/usr/abc/file" or just "file"'
expr $a : '.*/ $a
Example 3 Using // characters to simplify the expression
The addition of the // characters eliminates any ambiguity about the division operator and simplifies the whole expression.
# A better representation of example 2.
expr //$a : '.*/
Example 4 Returning the value of a variable
Returns the number of characters in $VAR.
expr $VAR : '.*'
EXIT STATUS
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.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWscpu |
+-----------------------------+-----------------------------+
SEE ALSO
sh(1), test(1), attributes(5), regexp(5)
DIAGNOSTICS
syntax error for operator/operand errors
non-numeric argument if arithmetic is attempted on such a string
division by zero if an attempt to divide by zero is made
BUGS
After argument processing by the shell, expr cannot tell the difference between an operator and an operand except by the value. If $a is an
=, the command:
expr $a = '='
looks like:
expr = = =
as the arguments are passed to expr (and they will all be taken as the = operator). The following works:
expr X$a = X=
Note: the match, substr, length, and index operators cannot themselves be used as ordinary strings. That is, the expression:
example% expr index expurgatorious length
syntax error
example%
generates the `syntax error' message as shown instead of the value 1 as you might expect.
SunOS 5.11 6 Jun 2000 expr(1B)