if tests the exit status of [. In the "if" branch, by definition, $? will be 0. It is the exit code of the command [ -s temp.txt ]. Yes, it is confusing to newbies that "open square bracket" is the name of a command, but that's what it is. You can call it test if you think that's less confusing.
Hi friends, :)
In a shell script i found the following if condition.
echo -n "Which version of $1 do you want to restore ('0' to quit)? : "
read desired
if ${desired:=1} -ge $index ] ; then
echo "$0: Restore canceled by user: index value too big." >&2
exit 1
fi
Can... (1 Reply)
i have a paramter data_date in which i am passing a string value.i want to find out another paramter file_date from this.the logic is given below
if day of data_date = sunday or monday
then
file_date=data_date-1
else
file_date=data_date-2
i am passing data_date as 20061027.
how can i... (3 Replies)
Hi,
I am trying to execute this command, but is it not working, says "`;' unexpected"
eval $lgrep $SAM_CMD ; if ; then ; echo "No Error" ; fi
What i want is, return the command output, if it is non zero, say "No Error".
Thanks, John. (21 Replies)
Executed the following if conditions .. and got different results .
only (( )) gave correct o/p with all scenarios .
Can anybody please let me know what is the difference between and ] and ((condition)) when used with if condition.
And why each condition gave different result.
1.... (2 Replies)
hi,
I have some problems in my simple script about the redirect echo stdout command inside a condition. Why is the echo command inside the elif still execute in the else command
Here are my simple script
After check on the two diff output the echo stdout redirect is present in two diff... (3 Replies)
HI
My doubt may be basic one but I need to get it clarified..
When i use "if" condition that checks for many AND, OR logical conditions
like
if ]; then
return 0
fi
Even the if condition fails it returns as zero.. Any clue..
But if i add else condition like
if ]; ... (2 Replies)
Hi all
Unix newbie - please be gentle
Am modifying an existing script to error trap a variable with a length of 0
#!/bin/bash
ipfile='/var/data/bin/ipaddress'
] && ipold="$(< "$ipfile" )"
ipnew="$( wget -q -O - checkip.dyndns.org | sed -e 's/.*Current IP Address: //;s/<.*$//' )"
#... (6 Replies)
o/p of my command is given below
My requirement is
if Pnumber is 0 then
stabilization.Build.2013
else
stabilization.PBuild.2013.3 (11 Replies)
Discussion started by: nikhil jain
11 Replies
LEARN ABOUT ULTRIX
test
test(1sh5)test(1sh5)Name
test - condition evaluation command
Syntax
test expr
[ expr ]
Description
The command evaluates the expression expr. If the value of expr is true, the command returns a zero exit status; otherwise, it returns a
nonzero exit status. The command also returns a nonzero exit status if no arguments are specified. The following primitives are used to
construct expr:
-r file True if file exists and is readable.
-w file True if file exists and is writable.
-x file True if file exists and is executable.
-f file True if file exists and is a regular file.
-d file True if file exists and is a directory.
-c file True if file exists and is a character special file.
-b file True if file exists and is a block special file.
-p file True if file exists and is a named pipe (fifo).
-u file True if file exists and its set-user-ID bit is set.
-g file True if file exists and its set-group-ID bit is set.
-k file True if file exists and its sticky bit is set.
-s file True if 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 non-zero.
s1 = s2 True if strings s1 and s2 are identical.
s1 != s2 True if strings s1 and s2 are not identical.
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, and -le may be used in
place of -eq.
These primitives can be combined with the following operators:
! unary negation operator.
-a binary and operator.
-o binary or operator (-a has higher precedence than -o).
( expr ) parentheses for grouping.
Note that all the operators and flags are separate arguments to the command. Note also that parentheses are meaningful to the Shell and
must be escaped. In the form of the command that uses square brackets ([]), instead of the word test, the brackets must be delimited by
blanks.
See Alsofind(1), sh5(1), test(1)test(1sh5)