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.
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)
Apologies for the utter triviality of this question, but we all have to start somewhere! I've also tried searching but this question is pretty vague so I didn't (a) really know what to search for or (b) get many relevant hits to what I did search for.
Anyway, I'm in the process of self-teaching... (1 Reply)
Hi.
How to change string variable in awk?
for example, I parse with awk script text file named some_name_with_extension.txt
I want to print only some_name in my script
....
varCompName = FILENAME
print varCompName
How to put not all symbols from FILENAME to variable?
thank you
This... (4 Replies)
Hey Guys,
I have text such as this.
28003,ALCORN,2
28009,BENTON,2
28013,CALHOUN,2
28017,CHICKASAW,2
47017,CARROLL,2
05021,CLAY,0
The last digit after the final "," is a variable value. This is the base file. I have to do further execution on this file later and I need to update the... (7 Replies)
I feel like it is just a matter of using the $ operators correctly, but I can't seem to get it...
hostname="network"
ip="192.168.1.1"
netmask=""
variables=( $hostname $ip $netmask )
for var in ${variables}
do
if ; then
$var="--"
fi
done
echo... (7 Replies)
Hi,
This is the first time I see something like this, and I don't why it happens.
Please give me some help. I am really appreciate it.
Basically I am trying to remove all empty lines of an input..
#!/bin/bash
set -e
set -x
str1=`echo -e "\nhaha" | grep -v ^$`
#str2=`echo -e "\n" |... (4 Replies)
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
Can you please suggest a easy way to do that ? (12 Replies)
Discussion started by: mohtashims
12 Replies
LEARN ABOUT DEBIAN
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.
-A file True if the file exists and is append-only.
-L file True if the file exists and is exclusive-use.
-Tfile True if the file exists and is temporary.
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.
a -nt b True if file a is newer than (modified after) file b.
a -ot b True if file a is older than (modified before) file b.
f -older t True if file f is older than (modified before) time t. If t is a integer followed by the letters y(years), M(months), d(days),
h(hours), m(minutes), or s(seconds), it represents current time minus the specified time. If there is no letter, it represents
seconds since epoch. You can also concatenate mixed units. For example, 3d12h means three days and twelve hours ago.
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
/src/cmd/test.c
SEE ALSO rc(1)TEST(1)