$> test.sh
Press Enter to select existing value
uid[scott]: # Selected Enter here.
uid --> scott
$> test.sh
Press Enter to select existing value
uid[scott]: aaaaa
0000000 141 141 141 141 141 012
a a a a a \n
6161 6161 610a
0000006
uid --> aaaaa
I still could not understand why I can't use [ ! -n string ] instead of [ -z string ] or vice-versa .
Here is what the reference page I am looking at says about these two condition checking flags for ksh.
Code:
-z string ---> True if length of string is zero
-n string ---> True if length of string is non-zero
Can someone explain what are true differences between -z, -n flags !!? Where can I find true reference for this?
Last edited by kchinnam; 05-19-2010 at 08:02 PM..
Reason: formatting adjustments
How to write this condition in ksh?
if myfile is empty or myfile does not exist
then
do action1
fi
is this OK?
if ] -o ] then
then
do action1
fi
Thanks. (3 Replies)
Hi,
Plz suggest me how can i change the date of a file.
Suppose my file has been created in some date and i want to give it present date.
How can i do this???? (2 Replies)
hi all,
i want use the variable value as a new variable name. print output of new variable.
for i in COMPUTER1 COMPUTER2
do
flag_name=${i}_FLAG
eval ${flag_name}=123
echo $i'_FLAG'
done
output is
COMPUTER1_FLAG
COMPUTER2_FLAG
i need output as
123
123 (2 Replies)
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Hi.
How to change string variable in awk?
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I want to print only some_name in my script
....
varCompName = FILENAME
print varCompName
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28017,CHICKASAW,2
47017,CARROLL,2
05021,CLAY,0
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Hi,
This is the first time I see something like this, and I don't why it happens.
Please give me some help. I am really appreciate it.
Basically I am trying to remove all empty lines of an input..
#!/bin/bash
set -e
set -x
str1=`echo -e "\nhaha" | grep -v ^$`
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I have a file hello.txt which was created today (today's date timestamp)
I wish to change its date timestamp (access, modified, created) to 1 week old i.e one week from now.
uname -a
SunOS mymac 5.11 11.2 sun4v sparc sun4v
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Discussion started by: mohtashims
12 Replies
LEARN ABOUT BSD
test
TEST(1) General Commands Manual TEST(1)NAME
test - condition evaluation utility
SYNOPSIS
test expression
DESCRIPTION
The test utility evaluates the expression and, if it evaluates to true, returns a zero (true) exit status; otherwise it returns 1 (false).
If there is no expression, test also returns 1 (false).
All operators and flags are separate arguments to the test utility.
The following primaries are used to construct expression:
-b file
True if file exists and is a block special file.
-c file
True if file exists and is a character special file.
-d file
True if file exists and is a directory.
-e file
True if file exists (regardless of type).
-f file
True if file exists and is a regular file.
-g file
True if file exists and its set group ID flag is set.
-h file
True if file exists and is a symbolic link.
-n string
True if the length of string is nonzero.
-p file
True if file is a named pipe
-r file
True if file exists and is readable.
-s file
True if file exists and has a size greater than zero.
-t [file_descriptor]
True if the file whose file descriptor number is file_descriptor (default 1) is open and is associated with a terminal.
-u file
True if file exists and its set user ID flag is set.
-w file
True if file exists and is writable. True indicates only that the write flag is on. The file is not writable on a read-only file
system even if this test indicates true.
-x file
True if file exists and is executable. True indicates only that the execute flag is on. If file is a directory, true indicates
that file can be searched.
-z string
True if the length of string is zero.
string
True if string is not the null string.
s1 = s2
True if the strings s1 and s2 are identical.
s1 != s2
True if the strings s1 and s2 are not identical.
n1 -eq n2
True if the integers n1 and n2 are algebraically equal.
n1 -ne n2
True if the integers n1 and n2 are not algebraically equal.
n1 -gt n2
True if the integer n1 is algebraically greater than the integer n2 .
n1 -ge n2
True if the integer n1 is algebraically greater than or equal to the integer n2 .
n1 -lt n2
True if the integer n1 is algebraically less than the integer n2 .
n1 -le n2
True if the integer n1 is algebraically less than or equal to the integer n2 .
These primaries can be combined with the following operators:
! expression
True if expression is false.
expression1 -a expression2
True if both expression1 and expression2 are true.
expression1 -o expression2
True if either expression1 or expression2 are true.
(expression)
True if expression is true.
The
-a operator has higher precedence than the -o operator.
GRAMMAR AMBIGUITY
The test grammar is inherently ambiguous. In order to assure a degree of consistency, the cases described in the IEEE Std 1003.2
("POSIX"), section D11.2/4.62.4, standard are evaluated consistently according to the rules specified in the standards document. All other
cases are subject to the ambiguity in the command semantics.
RETURN VALUES
The test utility exits with one of the following values:
0 expression evaluated to true.
1 expression evaluated to false or expression was missing.
>1 An error occurred.
BUGS
Named pipes are not implemented in 2.11BSD.
STANDARDS
The test function is expected to be IEEE Std 1003.2 ("POSIX") compatible.
7th Edition March 13, 1995 TEST(1)