man bash: Command substitution allows the output of a command to replace the command name, i.e will make the command's stdout available for e.g. variable assignment. cmp will not output anything if files are identical, or some explanatory text if not; neither of which you want to (or can) test for. You'd go for the exit code instead. Try
Trying to assign the entry variables like you showed in post#1 will fail as the while loop reading from a pipe is executed in a subshell that can't return it's variables to the parent shell, resulting in entry1 and entry2 not being set in the parent shell. Try "process substitution" for the ls command, or put ls's output into a file and read the variables from there.
Hi,
I am trying to use && set up to match two conditions within ksh:
if &&
then
'''Do something
if
somehow, I keep getting error message telling me that ] is missing.
What's wrong with my code?
Thanks a lot for your help! (1 Reply)
I'm totally new with bash programming and I don't get it how to put two conditions in one if statement. My code looks like this:
h=`date +%k`
if && ]; then$h is 10 but I don't get into my if statement. What's wrong here? (5 Replies)
I have a script that runs on multiple servers. What I want to do is have the script do the following:
if $(hostname) is equal to server or server2
then
TO_DIR=go
else
TO_DIR=stop
fi
I have tried:
if
if ]
Server is hpux.
any ideas? (1 Reply)
I have a script that runs every 15 minutes in cron that builds a web page.
It runs at 15, 28, 45 and 58 minutes past the hour. (pretty much evry 15 mins).
Every 2 hours from 6:28 to 18:28 it sends out emails if it finds errors. I do not want it sending email every single time it runs, every 15... (5 Replies)
is it possible to use multiple conditions in a CASE statement? And if so, what is the syntax? I'm trying to use one but can't seem to get it right. I want the statement to be
CASE $vendor OR $alias
condition 1) statements;
condition 2) statements;
etc.
esac
but I keep... (25 Replies)
Hello,
I'm trying to put together a script that involves pulling data from a config file. I'm attempting to write an if statement to validate one of the pieces of data from the config file, but I think I'm fat fingering it somehow.
$config{VALUE} is being pulled from a config file but can only... (4 Replies)
When I try the below if Condition with single condition its working fine.
But when I try to Club both its working . But giving wrong results.
In my case
cond1 = -f ${filename1} = true
cond2 = -f ${filename2} = true
But Cond1 & Cond2 is resulting in False ??? Please advise
... (5 Replies)
Hello,
I am using shell scripting and I am recieving odd results from my if statement
if
I want it to enter the loop only if L1 is equal to zero and one of the other criteria are filled, however it is entering at other times as well. What can i do to fix this? i tried seperating it... (6 Replies)
I was trying to write multiple conditions inside the if statement but its not working.
export VAR_NM=abc.txt
export CURR_DT=20131011
export PREV_DT=20131012
if &&
then
echo "Yes"
else
echo "NO"
fi
It should return Yes but returning NO always.Appreciate any help. (3 Replies)
#!/bin/bash
if &&
then
echo "True"
else
echo "False"
fi
Hi everyone, I am new to UNIX, here I have a if statement elevating two boolean conditions. I thought the output should be True because there are + in the statement. But it turns out to be False.
Can anyone... (3 Replies)
Discussion started by: mryuyu1111
3 Replies
LEARN ABOUT BSD
source
exec(1) User Commands exec(1)NAME
exec, eval, source - shell built-in functions to execute other commands
SYNOPSIS
sh
exec [argument...]
eval [argument...]
csh
exec command
eval argument...
source [-h] name
ksh
*exec [arg...]
*eval [arg...]
DESCRIPTION
sh
The exec command specified by the arguments is executed in place of this shell without creating a new process. Input/output arguments may
appear and, if no other arguments are given, cause the shell input/output to be modified.
The arguments to the eval built-in are read as input to the shell and the resulting command(s) executed.
csh
exec executes command in place of the current shell, which terminates.
eval reads its arguments as input to the shell and executes the resulting command(s). This is usually used to execute commands generated as
the result of command or variable substitution.
source reads commands from name. source commands may be nested, but if they are nested too deeply the shell may run out of file descrip-
tors. An error in a sourced file at any level terminates all nested source commands.
-h Place commands from the file name on the history list without executing them.
ksh
With the exec built-in, if arg is given, the command specified by the arguments is executed in place of this shell without creating a new
process. Input/output arguments may appear and affect the current process. If no arguments are given the effect of this command is to mod-
ify file descriptors as prescribed by the input/output redirection list. In this case, any file descriptor numbers greater than 2 that are
opened with this mechanism are closed when invoking another program.
The arguments to eval are read as input to the shell and the resulting command(s) executed.
On this man page, ksh(1) commands that are preceded by one or two * (asterisks) are treated specially in the following ways:
1. Variable assignment lists preceding the command remain in effect when the command completes.
2. I/O redirections are processed after variable assignments.
3. Errors cause a script that contains them to abort.
4. Words, following a command preceded by ** that are in the format of a variable assignment, are expanded with the same rules as a vari-
able assignment. This means that tilde substitution is performed after the = sign and word splitting and file name generation are not
performed.
EXIT STATUS
For ksh:
If command is not found, the exit status is 127. If command is found, but is not an executable utility, the exit status is 126. If a redi-
rection error occurs, the shell exits with a value in the range 1-125. Otherwise, exec returns a zero exit status.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWcsu |
+-----------------------------+-----------------------------+
SEE ALSO csh(1), ksh(1), sh(1), attributes(5)SunOS 5.10 17 Jul 2002 exec(1)