How can I use a variable that has the conditions for the if statement stored in it?
my test script
condition=" || || "
if "$condition"
then echo "true"
else echo "false"
fi
output
$ ./test2.sh
./test2.sh: line 3: || || : command not found
false (2 Replies)
Hi All,
I am trying to check if two variables have value assigned to it.
i am doing it like
if ]
then
echo "Please specify either single hostname or host file for the report"
usage
exit
fi
But its not working for it.Even i specify values for both variables it dont go... (6 Replies)
Hi, I have meaning to include an if condition statement in my code to check the directory for existing output files and if its existing i want the program to delete it before doing the succeeding command. i just dont know the correct syntax for it. thanks much guys, this forum has indeed been very... (4 Replies)
Urgent help with bash scripting
1- i am using grep to find a string called: tinker panic 0 in a file /etc/ntp.conf
if the string is not there, i want to add the strings in /etc/ntp.conf file in the first line of the file. if not do nothing or exit.
2- also i want to add # in front of the... (2 Replies)
I want to check (using bash condition test function) if string contains three spaces, ignoring last three spaces at the end of string.
string_to_report='foo bar foo bar '
string_to_ignore='foo bar ' (8 Replies)
In the below I can not seem to add a line that will add Not low if the statement in bold is not true or meet. I guess when the first if statement is true/meet then print low, otherwise print Not low in $(NF + 1). I am not sure how to correctly add this. Thank you :).
if(low <= $2 && $2 <=... (5 Replies)
Hi,
I need to perform the untar and rm operation if the file found is a .tar and does not have test.tar or hello.tar as the file names.
Below is the loop to check the same.
for tf in *.tar
do if ]
then found=1
... (1 Reply)
I wrote a code to find codons in a DNA string. The only problem I have is how do I make the code only work for a file with DNA. This means the file only has the characters a,c,g,t and no white space characters. (3 Replies)
Hi.
I wrote this small bash script, i want to compare second column from file1 with file2 if a pattern matches. Files are small and I am sure that pattern occurs only once. I think this can be rewritten into a awk one liner. Appreciate if someone could give me idea. Whole NR FNR confuse me :o
... (6 Replies)
Discussion started by: ctrld
6 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)