08-06-2008
question about echo $$
hi all
i have script
echo $$ >tmp
i understand thatecho $$ display some process id which is unique
is that correct ?
and my othere question is what is the maximum length that process-id can
be ?
the reason that i'm asking this is because i have a program which need to read the number of the process , and i don't know which length to give to the variable ,and how shall i define this variable as number or character ?
thanks in advance
10 More Discussions You Might Find Interesting
1. UNIX for Dummies Questions & Answers
Hi,
I would like to output the identical line to 2 text files, ie
output='blah'
echo $output > test1.txt
echo $output > test2.txt
Is there a way I could do that output with ONE command, ie
output='blah'
echo $output > test1.txt & test2.txt (I know that doesn't work)
Thanks for any... (1 Reply)
Discussion started by: msb65
1 Replies
2. Shell Programming and Scripting
Why do get 0 when i enter " echo $? " (1 Reply)
Discussion started by: JamieMurry
1 Replies
3. OS X (Apple)
Hello,
I am trying to send text to a USB to serial adaptor and then to an external speech synthesizer. I tried using the cat and echo commands with no luck. I have gotten some audio output from my synthesizer using Kermit a terminal emulator, so I am pretty sure my synthesizer and my USB to serial... (1 Reply)
Discussion started by: jamesapp
1 Replies
4. Shell Programming and Scripting
How can I get the following to prompt me for new values for the dacsrtrspans?
example I want to change the span #, sinktermmod, sinktermport, srctermdev and srctermport to new values.
old:
ADD DACSRTRSPAN-1-840 SINKTERMMODULE=8 SINKTERMPORT=94 SRCTERMDEV=1 SRCTERMPORT=1 SPANTYPE=T1_2... (0 Replies)
Discussion started by: tadzooks
0 Replies
5. Shell Programming and Scripting
echo `echo ` doesn't echoes anything. And it's logic. But
echo `echo `echo ` ` does echoes "echo". What's the logic of it? the `echo `echo ` inside of the whole (first) echo, echoes nothing, so the first echo have to echo nothing but echoes "echo"
(too much echoing :P):o (2 Replies)
Discussion started by: hakermania
2 Replies
6. UNIX for Dummies Questions & Answers
Hi all and tks in advance
I am working my way through 'Learning the bash Shell'. I cannot be sure if I really understand why "echo *" (my double quotes) returns all the files in the current directory.
I get the * ( wildcard) expansion of "*", and I think I understand that "echo" returns it's... (5 Replies)
Discussion started by: mdeh
5 Replies
7. UNIX for Advanced & Expert Users
Whats the difference between using date in these 2 methods? How exactly does the shell handle the first one different from the second one?
$ echo $date
$ echo $(date)
Tue Aug 16 03:10:25 EDT 2011 (5 Replies)
Discussion started by: cokedude
5 Replies
8. Shell Programming and Scripting
Hey all, so I wrote a pretty simple script. It's viewable here:
#!/bin/sh
FILE=`ls $1`
for filename in $FILE
do
echo $filename
`echo $filename | tr e 5 `
doneSo, as you can see it gets the list from a command line specified directory. It then loops through, echoes the filename, and then... (7 Replies)
Discussion started by: lowExpectations
7 Replies
9. Shell Programming and Scripting
Apologies, probably a really simple problem:
I've got a text file (nh.txt) with this in it:
user1 email1 email2
user2 email1 email2
etc
With the following basic script:
for tline in $(cat nh.txt)
do
echo "**********"
echo $tline
done
... (3 Replies)
Discussion started by: nelmo
3 Replies
10. Shell Programming and Scripting
Hi
I want to use echo command as below
echo 'dir=' $1 ' dir|file|home'
i need output like below :
echo 'dir=' $1 ' dir|file|home' pp13dff
Output
dir=pp13dff dir|file|home (4 Replies)
Discussion started by: asavaliya
4 Replies
LEARN ABOUT FREEBSD
mktemp
MKTEMP(1) BSD General Commands Manual MKTEMP(1)
NAME
mktemp -- make temporary file name (unique)
SYNOPSIS
mktemp [-d] [-q] [-t prefix] [-u] template ...
mktemp [-d] [-q] [-u] -t prefix
DESCRIPTION
The mktemp utility takes each of the given file name templates and overwrites a portion of it to create a file name. This file name is
unique and suitable for use by the application. The template may be any file name with some number of 'Xs' appended to it, for example
/tmp/temp.XXXX. The trailing 'Xs' are replaced with the current process number and/or a unique letter combination. The number of unique
file names mktemp can return depends on the number of 'Xs' provided; six 'Xs' will result in mktemp selecting 1 of 56800235584 (62 ** 6) pos-
sible file names.
If mktemp can successfully generate a unique file name, the file is created with mode 0600 (unless the -u flag is given) and the filename is
printed to standard output.
If the -t prefix option is given, mktemp will generate a template string based on the prefix and the TMPDIR environment variable if set. The
default location if TMPDIR is not set is /tmp. Care should be taken to ensure that it is appropriate to use an environment variable poten-
tially supplied by the user.
If no arguments are passed or if only the -d flag is passed mktemp behaves as if -t tmp was supplied.
Any number of temporary files may be created in a single invocation, including one based on the internal template resulting from the -t flag.
The mktemp utility is provided to allow shell scripts to safely use temporary files. Traditionally, many shell scripts take the name of the
program with the pid as a suffix and use that as a temporary file name. This kind of naming scheme is predictable and the race condition it
creates is easy for an attacker to win. A safer, though still inferior, approach is to make a temporary directory using the same naming
scheme. While this does allow one to guarantee that a temporary file will not be subverted, it still allows a simple denial of service
attack. For these reasons it is suggested that mktemp be used instead.
OPTIONS
The available options are as follows:
-d Make a directory instead of a file.
-q Fail silently if an error occurs. This is useful if a script does not want error output to go to standard error.
-t prefix
Generate a template (using the supplied prefix and TMPDIR if set) to create a filename template.
-u Operate in ``unsafe'' mode. The temp file will be unlinked before mktemp exits. This is slightly better than mktemp(3) but still
introduces a race condition. Use of this option is not encouraged.
EXIT STATUS
The mktemp utility exits 0 on success, and >0 if an error occurs.
EXAMPLES
The following sh(1) fragment illustrates a simple use of mktemp where the script should quit if it cannot get a safe temporary file.
tempfoo=`basename $0`
TMPFILE=`mktemp /tmp/${tempfoo}.XXXXXX` || exit 1
echo "program output" >> $TMPFILE
To allow the use of $TMPDIR:
tempfoo=`basename $0`
TMPFILE=`mktemp -t ${tempfoo}` || exit 1
echo "program output" >> $TMPFILE
In this case, we want the script to catch the error itself.
tempfoo=`basename $0`
TMPFILE=`mktemp -q /tmp/${tempfoo}.XXXXXX`
if [ $? -ne 0 ]; then
echo "$0: Can't create temp file, exiting..."
exit 1
fi
SEE ALSO
mkdtemp(3), mkstemp(3), mktemp(3), environ(7)
HISTORY
A mktemp utility appeared in OpenBSD 2.1. This implementation was written independently based on the OpenBSD man page, and first appeared in
FreeBSD 2.2.7. This man page is taken from OpenBSD.
BSD
December 30, 2005 BSD