Find non-empty subdirectories

find . -mindepth 1 -maxdepth 1 -not -empty -type d source: https://stackoverflow.com/questions/815668/how-to-list-non-empty-subdirectories-on-linux#comment625237_8156...

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tar excluding some files

tar -pczf MyFile.tar.gz /home/user/myDirectory/ --exclude=pattern Example: Excluding files whose names end in '.txt'. tar -pczf MyFile.tar.gz /home/user/myDirectory/ --exclude='*.tx...

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tar excluding directories

tar -pczf MyFile.tar.gz /home/user/myDirectory/ --exclude="./directoryToExclude1" --exclude="./directoryToExclude2" Note that there is no "/" at the end of the path to the directory to exclu...

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Swap columns in text file with awk

To swap column 2 and 3 in a 4 column file: awk -F, '{print $1,$3,$2,$4}' OFS=; "FILE" > NEW_FILE where: OFS: indicates the separator character(';' in the example above). FILE: original file. NEW_FILE: new file with the chang...

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Shell Script 'action' Command

'action' is defined inside a library called functions. You have to source your script first with this library in order to use it. This library is a distro distribution dependent and none of these distro libraries are compatible with the others. In Ubuntu is /lib/lsb/init-functions, SuSE has /etc/rc.status and in Centos is /etc/rc.d/init.d/functions. Some distributions don't use it at all. Example...

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Set or Change System Hostname

This will return the current hostname $ hostname MyHostame To set hostname immediately: $ hostname [MY_HOSTNAME] This will change the hostname of your system immediately, but the original hostname will be restored upon next reboot. To set hostname to be permant follow the instructions below. For systemd based distributions(newer version of different Linux distributions such as latest Ubuntu, Debian,...

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shmget errno 22 EINVAL: "Invalid Argument"

The man page says: EINVAL A new segment was to be created and size < SHMMIN or size > SHMMAX, or no new segment was to be created, a segment with given key existed, but size is greater than the size of that segment. This means that a memory segment still persists in the system. If your process is no longer running, run the ipcs command and remove the segment with ipcrm. [root@myhost]# ipcs ------...

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