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Three lines tip
Do you have a tip/hack that's max. three lines long??
How do I capture the output of “top” to a file?
The command top is a very useful tool to capture information about process running on Linux. Many times this information may need to be captured to a file. This can be done with the following command:
top -b -n1 > /tmp/top.txt
This will run top once write the output to a file and exit.
The command top can also be run so that it will give multiple reports. To run top 5 times and wait 5 seconds between each output the command would be:
top -b -n5 -d5 > /tmp/top.txt
Removing whitespaces from filename
# i in *.[jJ][pP][gG]; do mv "$i" $(echo "$i" | sed "s/ /_/g"); done
ali
# rename 's/ /_/' *.[jJ][pP][gG]
:)
How to get Webserver Version
# printf "HEAD / HTTP/1.0nn" | nc $server 80 | grep Server
Spliting .tgz file on the fly
tar -czf /dev/stdout $(DIRECTORY_OR_FILE_TO_COMPRESS) | split -d -b $(CHUNK_SIZE_IN_BYTES) - $(FILE_NAME_PREFIX)
putting them together agian
cat $(FILE_NAME_PREFIX)* >> /dev/stdout | tar -xzf /dev/stdin
Compile on SMP machines
export MAKEFLAGS=“-j3”
Patch & Diff
$ diff -c prog.c.old prog.c > prog.patch $ patch < prog.patch
Printing network traffic
% sudo tcpdump -Atq -s 0 -i en1
-i en1 will display traffic on your airport card. Use en0 (or nothing, for most systems) for built-in ethernettage. You can add a host line to limit output to a particular host
% sudo tcpdump -Atq -s 0 -i en1 host foobar.com
Couting openfiles per user
# lsof | grep ' root ' | awk '{print $NF}' | sort | wc -l
Of course, if you want to drop the count and show the actual processes, you can run:
# lsof | grep ' root '
How to check is service is tcpwrapper enable
# ldd `which sshd` | grep -i libwrap
or
# strings `which sshd` | grep -i libwrap