I would like to know if it's possible to append data into a variable, rather than into a file. Although I can write information into a temporary file in /tmp, I'd rather if possible write into a variable, as I don't like the idea that should my script fail, I'll be polluting the server with messy temp files. Currently my script has a for loop containing:
echo "$line" >> $tmpdir
where $tmpdir represents a filename. Is there a way round this?
If all you are doing is echoing a value, just assign the value to a variable instead:
If it's a real command, use command substitution, e.g.:
I need to know how to record the hostname, date/time and all of the process and send it all to one file. I know that the commands I need are hostname, date and ps but I don't know how to do them all and send them all to the same file. Please help! (1 Reply)
Hi,
Am trying to write a shell script which will append a header and a footer to an existing file. Header will contain details like the current date while the footer will contain the no: of records listed in the file.
I know we can use the CAT command, but i have no clue abt the syntax to... (4 Replies)
Hi ...
I am having a string in the buffer .. It is binary data it may contain space . When i try to append a space in using strcpy it is taking the inbetween \n as the end and appending space ..
How to append space in the binary data in C ?? please let me know
Thanks in advance,
Arun. (2 Replies)
Hey, I'm creating a custom useradd script, and I'm giving the option to add secondary groups. Basically what I want to do is ask for the name of the group, you type in the group you want to add, it assigns that group name to the variable $sgroup. Then the scripts asks if you want add another. If... (0 Replies)
Hi.
I wrote a very simple script and it doesn't work :(
It is supposed to go to a certain directory, execute some command and append the output to the file "expo.dat"
what it does is that it writes to the file only one entery. I dont know if Im using the write synthax for "append". Here is... (3 Replies)
I have on file abc.txt
abc.txt:
20090807
Now I want to delete empty lines which has tap/whit spaces from abc.txt .and store the date value in the file into variable.some processs will update the this file with some date . if the process updtes thiis file with empty string , write the... (3 Replies)
A friend contacted me recently with an interesting question. We got something worked out, but I'm curious what answers you all can come up with.
Given a shell script (in bash) that processes a bunch of data and appends it to a file, how would you append the date, time, and a filename to the... (6 Replies)
I have a Query!
by using command
cat >> file1 we can append data's to a already existing file, Similarly is it possible to append a data to a variable.
Thanks in Advance!! (2 Replies)
I am familiar with scripting, but I am trying to see if there is an easy way to append files from similar files into one file. For example, if there is file1_20121201, file1_20121202, file1_20121203,
file2_20121201, file2_20121202, file2_20121203
I want to be able to combine all the data from... (3 Replies)
Hi
I have a file called text.txt contains
x
y
z
when i run a command i will get output like below
x 20
z 30
i want to insert x, z value in text.txt file and should be like this
x 20
y 0
z 30
can anyone help me please? (1 Reply)
Discussion started by: siva kumar
1 Replies
LEARN ABOUT NETBSD
mktemp
MKTEMP(1) BSD General Commands Manual MKTEMP(1)NAME
mktemp -- make temporary file name (unique)
SYNOPSIS
mktemp [-dqu] [-p tmpdir] {-t prefix | template ...}
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 testing roughly 26 ** 6 combinations.
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. The default location of the temporary directory can be overridden with the -p tmpdir
option. The template string created will consist of the prefix followed by a '.' and an eight character unique letter combination. 'Xs' in
the prefix string will be treated as literal. If an additional template argument is passed, a second file will be created. Care should be
taken to ensure that it is appropriate to use an environment variable potentially supplied by the user.
Any number of temporary files may be created in a single invocation using multiple template arguments, also a single one based on the inter-
nal template with the -t option value as filename prefix.
At least one template argument or the -t option must be present.
mktemp 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. If -t prefix and template are both
given, prefix will not apply to 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 with a value of 0 on success, and 1 on any failure.
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.
TMPFILE=`mktemp /tmp/${0##*/}.XXXXXX` || exit 1
echo "program output" >> $TMPFILE
To allow the use of $TMPDIR:
TMPFILE=`mktemp -t ${0##*/}` || exit 1
echo "program output" >> $TMPFILE
In this case, we want the script to catch the error itself.
TMPFILE=`mktemp -q /tmp/${0##*/}.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
The mktemp utility appeared in NetBSD 1.5. It has been imported from FreeBSD, the idea and the manual page were taken from OpenBSD.
BSD August 15, 2009 BSD