true(1) General Commands Manual true(1)Name
true, false - provide test for status values
Syntax
true
false
Description
The and commands are usually used in a Bourne shell script. They test for the appropriate status "true" or "false" before running (or
failing to run) a list of commands.
Examples
while true
do
command list
done
Diagnostics
The command has exit status zero.
See Alsocsh(1), sh(1)true(1)
Check Out this Related Man Page
TEST(1) General Commands Manual TEST(1)NAME
test - condition command
SYNOPSIS
test expr
DESCRIPTION
test evaluates the expression expr, and if its value is true then returns zero exit status; otherwise, a non zero exit status is returned.
test returns a non zero exit if there are no arguments.
The following primitives are used to construct expr.
-r file true if the file exists and is readable.
-w file true if the file exists and is writable.
-f file true if the file exists and is not a directory.
-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 associated with a terminal device.
-z s1 true if the length of string s1 is zero.
-n s1 true if the length of the string s1 is nonzero.
s1 = s2 true if the strings s1 and s2 are equal.
s1 != s2 true if the strings s1 and s2 are not equal.
s1 true if s1 is not the null string.
n1 -eq n2
true if the integers n1 and n2 are algebraically equal. Any of the comparisons -ne, -gt, -ge, -lt, or -le may be used in place of
-eq.
These primaries may be combined with the following operators:
! unary negation operator
-a binary and operator
-o binary or operator
( expr )
parentheses for grouping.
-a has higher precedence than -o. Notice that all the operators and flags are separate arguments to test. Notice also that parentheses
are meaningful to the Shell and must be escaped.
SEE ALSO sh(1), find(1)TEST(1)
I'm running Digital Unix True64 system. version4.0. My CDE is shutoff. How can I start the CDE. When I boot my system I don't even get graphic startup picture in the beginn. I've tried to activate thourgh Graphical UI Selection Facility in /usr/sbin/setup.But all I have is alot of inactive... (12 Replies)
Hi guys,
I'm new to unix but loving it!! BUT this is driving me nuts as i can't work out the best way to do it.
I have a while true loop that i use to monitor something. For my own reasons in ths script i have disabled the CTRL C using the trap command. But i want to put in a option to exit... (5 Replies)
Hi All,
i have an input below.
As long as "x= 1" , i would want to capture 2 lines using sed or awk
for eg :
0001 x= 1 $---------------------------------..-.--..
0001 tt= 137 171 423 1682 2826 0
Pls help. Thanks in advance.
Note that the number of lines in each block do... (37 Replies)
Hallo everybody
I am having a shell script called auto_run.sh in that only the first line works.
the second line which has sed command is working only at the # prompt. not within the shell script. What could be the reason.
*... sed 's/ //g' KTI >abc works in another shell script without the... (6 Replies)
I'm using clustered zones on my machine. i'm only at the test phase of my design and ultimately the oracle zones will be using VxVM.
When the testing phase is complete, VxVM will be used in the containers. It is necessary for VxVM to run in the global zone for the containers to use it (is... (5 Replies)
I have the following code and for some reason when I call the program using
/home/tcdata/tatsh/trunk/hstmy/bin/bash/raytrac.bash --cmod=jcdint.cmod
I get
hasArgument =
hasArgument = true
Somehow the array element is returning even though I have not chosen the option.
... (41 Replies)
Okay, I need some nerd magic here! LOL!
Using a bash script, I have a folder that I'd like to remove upon uninstalling a package. That part is simple but what isn't simple is taking into consideration a 'reinstall' or 'upgrade' of that same package.
By default, 'reinstalling' or 'upgrading'... (8 Replies)
Script for if characters from positions 7-15 are matching with characters from position 211-219 then replace all char from 211-219 with 9 space.
Total length of record is 420. Here is the specification of the data in file.
Position Field Data Type... (5 Replies)
I'm extremely new to shell scripting so I apologize for the crudeness of my descriptions. I am editing a script that will write files (e.g. Job0_A.com, Job1_A.com, etc.) and then run them through a program called gaussian (computational chemistry program). The script will then take the output files... (10 Replies)
I am having trouble getting mailx to send multiple Bcc mails out without everyone in the list of recipients seeing everyone else's email addresses. I looked at the man pages of my system and seem to be following the syntax correctly, but the mails still go out as if I were just putting in a list of... (7 Replies)
Hi,
I have the following txt file List_With_Duplicates.txt;
a,1,1
b,3,4
c,5,2
d,6,1
e,3,3
f,3,7
When I run the command
awk -F ',' '{if($2==$3){print $1","$2","$3}}' List_With_Duplicates.txt I get the following output;
a,1,1
e,3,3
This works! as I've compared the 2nd & 3rd... (7 Replies)
Hi everyone
I just got my hands on a T5120 running Sol10. As far as I've read, the T2 chip has a built-in hardware number generator. My question is: how can I access it to get random numbers in either C or Fortran? I'm using Sun Studio 12.4.
I am currently trying to write an... (13 Replies)
Hello,
This is a bit complicated for me.
My scenario in MyFile:
Search string1,
When string1 is found, grep the line containing string1, go back over that line in upward direction and grep the first line containing string2.
Here is an example:
MyFile
His email address... (17 Replies)
I have a csv file as given below,
org1 org2 org3 org4 org5
gene1 100 80 90 80 150
gene2 30 70 50 50 115
gene3 40 120 60 40 105
gene4 20 72 40 60 20
I need to replace the fields are having values greater than 100 with "TRUE". I used the following commands to replace... (6 Replies)