Use quotes around it, so you can avoid variable expansion in shell.
What is that, pamu?
Variable expansion will be done by the shell in any case (in case of double-quotes). The double-quotes are to retain the embedded spaces and/or to tell the shell that the parameter exists (in case of null strings) in case of [..] construct.
You don't require the quotes in case [[..]] construct (unless you are testing strings as is).
Also, in the [[..]], globbing is not done.
In ksh88,
Last edited by elixir_sinari; 10-01-2012 at 08:38 AM..
This User Gave Thanks to elixir_sinari For This Post:
hi, unix gurus.
i am wondering if someone can give me a clear explanation of the differneces between parentheses and brackets, both single and double.
i have heard that double parentheses (( are used for numerical expressions and that single brackets [ are used for strings. but i see... (1 Reply)
One of the senior administrators gave me a shell script to modify and it begins as follows:
if ] && ]
{more code follows}
Why the double square brackets? (10 Replies)
Hi
First apologies if this has been raised before.
I've got the following in a ksh script:
if ]
For some reason this does not work. But if I remove the double square brackets to:
if
This works.
I thought ksh supported the ]. Or is there more to it?
Thanks in advance. (3 Replies)
Hi,
I just came across an interesting shell script syntax like the one below:
] && (trap 'rm -rf ${WORK_DIR}/*.$$; echo "\n\nInterrupted !!\n\n"; exit 4' 1 2 3 15)
Can someone please explain the code snippet above?
The trap command bit is fine but ] && is the hazy part.
Generally we use an... (2 Replies)
Hi All,
I have a text file which looks like this:
computer programming
systems engineering
I want to get rid of these square brackets and also the text that is inside these brackets. So that my final text file looks like this:
computer programming
systems engineering
I am using... (3 Replies)
I wanted to compare the value inside the Squre bracket after Colon ( : ) based on any value(seperated by or operator | ) inside the variable Thread and if match found then wnated to store in output file
Input file :
20140320 00:08:43.918 INO 35] - Corporate hub is
20140320 00:08:43.918... (2 Replies)
I wanted to store the number inside the square bracket between colon( : ) and closing suqre bracket(]) in some variable.
Suppose I have lines like :
Input file :
20140320 00:08:23.846 INFO 84] - anything in line
20140320 00:08:23.846 Test 589] - Virtual and lab lab anything... (18 Replies)
Hi All,
Hope you all are doing good. Yesterday in my project i came across a scenario which i can not guess why it was working in one region and why it was not in another region. Please find my issue below.
I am using AIX version 6.0 of UNIX in my project, in shell scripting i have the... (1 Reply)
Discussion started by: mad man
1 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)