Can you use cat to send the first 25 lines of a file to the printer? I'm thinking I can pipe it with '|' but I'm not school to check printer output.
With the 'nl' used, all lines are numbered on the print out, but how does one number only the blank lines?
Thanks:) (1 Reply)
Hi,
I wnat to read a fiel line by line and store each line in a variabel, so I made a for loop:
for i in `cat file` ; do
#do sth.
done;
The problem is, that in the file, there are lines with only asterisks like this... (3 Replies)
Not sure how to do this exactly.. just want to take the first 100 lines of a file and cat it out into a second file. I know I can do a more on a file and > it into a different file, but how can I make it so only the first 100 lines get moved over? (1 Reply)
I want to cat a file with only show the line contain '/bin/bash' but don't show the line contain 'load' (don't show if the line contain 'load' and '/bin/bash' together), how to type in the command? thk a lot! (2 Replies)
I am looking for a command to take files with a specific date and cat them all into big file. I know I can use commands to list all of the files from a certain date. But I want to do that and take those files and make on large files containing all of them.
Any help would be great. This is being... (1 Reply)
Hi,
I have two files
one.txt
laptop
boy
apple
two.txt
unix
linux
OS
openS
I want to split one.txt into one line each and concatenate it with the two.txt
output files
onea.txt
laptop (4 Replies)
Hi All,
I have stumbled upon very unique issue. In my script I am doing cat file and then greping and cutting so as to assign the value to variable. My file is,
<mxc_tl_load_extractdata_prop.bsh>
DB_USER=test_oper
hostname=xxx
FTP_USER=test1_operate
MAIL_LIST=xxx@yyy.com... (1 Reply)
Hello,
I'm on a remote computer by SSH. How can I get the output of "cat file" into a file on the local computer?
I cannot use scp, because it's blocked.
something like:
ssh root@remote_maschine "cat /file" > /locale_machine/file
:rolleyes: (2 Replies)
Discussion started by: borsti007
2 Replies
LEARN ABOUT REDHAT
urandom
RANDOM(4) Linux Programmer's Manual RANDOM(4)NAME
random, urandom - kernel random number source devices
DESCRIPTION
The character special files /dev/random and /dev/urandom (present since Linux 1.3.30) provide an interface to the kernel's random number
generator. File /dev/random has major device number 1 and minor device number 8. File /dev/urandom has major device number 1 and minor
device number 9.
The random number generator gathers environmental noise from device drivers and other sources into an entropy pool. The generator also
keeps an estimate of the number of bit of the noise in the entropy pool. From this entropy pool random numbers are created.
When read, the /dev/random device will only return random bytes within the estimated number of bits of noise in the entropy pool.
/dev/random should be suitable for uses that need very high quality randomness such as one-time pad or key generation. When the entropy
pool is empty, reads to /dev/random will block until additional environmental noise is gathered.
When read, /dev/urandom device will return as many bytes as are requested. As a result, if there is not sufficient entropy in the entropy
pool, the returned values are theoretically vulnerable to a cryptographic attack on the algorithms used by the driver. Knowledge of how to
do this is not available in the current non-classified literature, but it is theoretically possible that such an attack may exist. If this
is a concern in your application, use /dev/random instead.
CONFIGURING
If your system does not have /dev/random and /dev/urandom created already, they can be created with the following commands:
mknod -m 644 /dev/random c 1 8
mknod -m 644 /dev/urandom c 1 9
chown root:root /dev/random /dev/urandom
When a Linux system starts up without much operator interaction, the entropy pool may be in a fairly predictable state. This reduces the
actual amount of noise in the entropy pool below the estimate. In order to counteract this effect, it helps to carry entropy pool informa-
tion across shut-downs and start-ups. To do this, add the following lines to an appropriate script which is run during the Linux system
start-up sequence:
echo "Initializing kernel random number generator..."
# Initialize kernel random number generator with random seed
# from last shut-down (or start-up) to this start-up. Load and
# then save 512 bytes, which is the size of the entropy pool.
if [ -f /var/random-seed ]; then
cat /var/random-seed >/dev/urandom
fi
dd if=/dev/urandom of=/var/random-seed count=1
Also, add the following lines in an appropriate script which is run during the Linux system shutdown:
# Carry a random seed from shut-down to start-up for the random
# number generator. Save 512 bytes, which is the size of the
# random number generator's entropy pool.
echo "Saving random seed..."
dd if=/dev/urandom of=/var/random-seed count=1
FILES
/dev/random
/dev/urandom
AUTHOR
The kernel's random number generator was written by Theodore Ts'o (tytso@athena.mit.edu).
SEE ALSO
mknod (1)
RFC 1750, "Randomness Recommendations for Security"
Linux 1997-08-01 RANDOM(4)