It seems I was busy editing my response after you had replied. I'm sorry. I hadn't noticed. I tried to restore it so your mention to my suggestion makes sense.
If the original location of stderr is stored in file descriptor 3, you can permanently restore it using:
With regard to testing the validity of a file descriptor (in this case, stderr), I suppose you can attempt to duplicate a descriptor and then test the exit status of the exec:
In that script, 5 is assumed to be an unused descriptor. If it is not, choose another number. Also, that should only work with interactive shells. In non-interactive shells, an exec failure will cause the shell to exit (assuming it's compliant with the posix standard sh).
If anyone knows of a better, more elegant, way to do this in sh, please do share your expertise (if it's not a portable solution, please mention in which environments you know it to work).
Hi,
I have small script written in korn shell. When it is called from different script, its dumping core, but no core dump when we run it standalone.
And its not dumping core if we run the script using "/bin/sh" instead of "ksh"
Can some body please help me how to resolve this issue.
... (9 Replies)
Unix gurus,
I have a piece of code as below.
] && INST="${ORACLE_SID}" || INST="${TWO_TASK}"
I know that the above code can be used in lieu of an IF construct. I also know that the above code can be extended for the "true" condition to include more than one command (as below):
... (8 Replies)
Hi everyone,
I`ll try to be most clear I can explaining my help request.
I have 2 folders
Folder A-->This folder receives files through FTP constantly
Folder B-->The files from Folder A are unzipped and then processed in Folder B
Sometimes Folder A doesn`t contain all... (2 Replies)
Hi,
I have line in input file as below:
3G_CENTRAL;INDONESIA_(M)_TELKOMSEL;SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL
My expected output for line in the file must be :
"1-Radon1-cMOC_deg"|"LDIndex"|"3G_CENTRAL|INDONESIA_(M)_TELKOMSEL"|LAST|"SPECIAL_WORLD_GRP_7_FA_2_TELKOMSEL"
Can someone... (7 Replies)
Hi,
Could anyone please shed some light on the following script lines and what is it doing as it was written by an ex-administrator?
cat $AMS/version|read a b verno d
DBVer=$(/usr/bin/printf "%7s" $verno)
I checked that the cat $AMS/version command returns following output:
... (10 Replies)
While going through a script, i came across few syntax which I am not aware of what they exactly means.
@ cnt = 1
@ num_all = `echo $var`
What is the significance of "@" here. What is it called? (3 Replies)
I want to be able to take a file name and then use sedto paste that text into the file.
I believe I know how to do the latter portion of pasting into the file at the location I want, but I do not know how to "copy" the file name to the "clipboard" for pasting.
Ideally I want to be able to... (1 Reply)
Hi Guys,
From past some days, I am getting an error in /var/adm/messages which is as shown below.
XXXXX02:/# cat /var/adm/messages |tail
Sep 16 15:28:14 XXXX02 EV_AGENT: Agent Main --Estream construct failed. Err: EMULSocket::recv()
Sep 16 15:31:49 XXXX02 EV_AGENT: Agent main --... (2 Replies)
How to use "mailx" command to do e-mail reading the input file containing email address, where column 1 has name and column 2 containing “To” e-mail address
and column 3 contains “cc” e-mail address to include with same email.
Sample input file, email.txt
Below is an sample code where... (2 Replies)
Hello.
System : opensuse leap 42.3
I have a bash script that build a text file.
I would like the last command doing :
print_cmd -o page-left=43 -o page-right=22 -o page-top=28 -o page-bottom=43 -o font=LatinModernMono12:regular:9 some_file.txt
where :
print_cmd ::= some printing... (1 Reply)
Discussion started by: jcdole
1 Replies
LEARN ABOUT ULTRIX
exec
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)