What is the difference between test expr VS [ expr ].
For example :
and
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 appreciated,
Last edited by pludi; 12-03-2009 at 07:21 AM..
Reason: code tags, please...
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)
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)
$ 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)
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 $1'}`
b=`cat... (1 Reply)
i have been told that 'let' is faster than 'expr' in terms of performance.
Is this correct? if yes, why is it so?
i am not able to see any performance difference in small arithmetic operations.
Thanks (3 Replies)
Hi All,
I'm writing a shell script in KSH, where I want to store the filename, total record count and actual record count of all the source files. The source files reside in 4 different sub-folders under the same root folder.
Below is code:
#!/usr/bin/ksh... (6 Replies)
Hi,
I have a text file where i define all the inputs to my shell script:
IP=1.2.3.4
PC=1234
In the shell script, i am trying to read the input variables from the above mentioned text file:
#!/bin/bash
#usage
IP=expr cat /tmp/input.txt | grep IP| cut -d "=" -f2
PC=expr cat... (4 Replies)
HI there
I am trying to understand Shell scripting to create my own, I am attempting a few examples can anyone tell me what this means?n=$( expr $n + 1)Tried looking on the internet, but just cannot find its anywhere :( .Help please (4 Replies)
Discussion started by: steve2015
4 Replies
LEARN ABOUT PLAN9
test
TEST(1) General Commands Manual TEST(1)NAME
test - set status according to condition
SYNOPSIS
test expr
DESCRIPTION
Test evaluates the expression expr. If the value is true the exit status is null; otherwise the exit status is non-null. If there are no
arguments the exit status is non-null.
The following primitives are used to construct expr.
-r file True if the file exists (is accessible) and is readable.
-w file True if the file exists and is writable.
-x file True if the file exists and has execute permission.
-e file True if the file exists.
-f file True if the file exists and is a plain file.
-d file True if the file exists and is a directory.
-s file True if the file exists and has a size greater than zero.
-t fildes True if the open file whose file descriptor number is fildes (1 by default) is the same file as /dev/cons.
s1 = s2 True if the strings s1 and s2 are identical.
s1 != s2 True if the strings s1 and s2 are not identical.
s1 True if s1 is not the null string. (Deprecated.)
-n s1 True if the length of string s1 is non-zero.
-z s1 True if the length of string s1 is zero.
n1 -eq n2 True if the integers n1 and n2 are arithmetically equal. Any of the comparisons -ne, -gt, -ge, -lt, or -le may be used in place
of -eq. The (nonstandard) construct -l string, meaning the length of string, may be used in place of an integer.
These primaries may be combined with the following operators:
! unary negation operator
-o binary or operator
-a binary and operator; higher precedence than -o
( expr ) parentheses for grouping.
The primitives -b, -u, -g, and -s return false; they are recognized for compatibility with POSIX.
Notice that all the operators and flags are separate arguments to test. Notice also that parentheses and equal signs are meaningful to rc
and must be enclosed in quotes.
EXAMPLES
Test is a dubious way to check for specific character strings: it uses a process to do what an rc(1) match or switch statement can do. The
first example is not only inefficient but wrong, because test understands the purported string "-c" as an option.
if (test $1 '=' "-c") echo OK # wrong!
A better way is
if (~ $1 -c) echo OK
Test whether is in the current directory.
test -f abc -o -d abc
SOURCE
/sys/src/cmd/test.c
SEE ALSO rc(1)TEST(1)