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Merging catalogs and creating unique identifier in bash

For a certain project I had created a number of photometric catalogs, each one corresponding to a specific observing field. I would like to construct the final (merged) one but for this I needed to add a unique source identifier at the beginning of each row. I decided to create a F#-**** tag for each […]

Shared folder in linux

Suppose that we want to create a folder in which multiple users will have full access (which means that they will be able to read, write, and execute). We create the folder (under ‘/’ in this example, although it can be anywhere else): sudo mkdir test which has the following permissions: drwxr-xr-x 2 root root […]

Installing matplotlib through pip but no plot displayed

The easiest way to install any Python package is through PyPI. So, matplotlib is not an exception and we installed it on a CentOS (v6.4) machine without any errors (of course after updating numpy). But when we tried to plot something we couldn’t see anything. This is actually a backend issue, and when we installed […]

Updating clock time through terminal

In my Fedora 14 desktop I keep losing minutes without knowing how and why (doesn’t the clock update automatically?). At the beginning I tried to change the file /etc/ntp.conf (edit it and change the parameter server to: ‘server pool.ntp.org’; 1) as perhaps the server did not respond correctly. I tried to update by: ntpdate pool.ntp.org […]

Fast notes on screen

> list sessions: screen -ls > resume session: screen -r > reattach (if necessary detach first): screen -d -r > detach session: screen -d > detach session (while running – keyboard shortcut): “ctrl+a”+”d” > kill session (inside session): “Ctrl+a”+”:quit” or the more obvious … “exit” > kill session (outside, list sessions first): screen -S session_number […]

Linux backup and restore filesystem –notes

A quick note on how to backup and restore (if necessary) the filesystem. We go to the root directory (/) and as root we run: tar cvpzf backup.tgz –exclude=/lost+found –exclude=/backup.tgz / c: create new archive v: verbose p: preserve permissions z: gzip f: use file (name of file=backup.tgz) We exclude all the directories that we […]

Zip multiple directories separately

In order to zip simultaneously a number of directories, but keep them separate, the following command will just do the job (in bash): for i in *; do zip -r $i.zip $i; done (caution: all directories inside which this command is executed will be zipped, so make a separate directory only to create the zip […]

VStar conflicts with java used

VStar is a multi-platform variable star visualisation and analysis tool, developed under the CitizenSky project and the AAVSO. Its use is straightforward if java is installed. But you should be carefull what java you are using… I tried to use VStar in two different machines running Ubuntu 10.10 64bit and Fedora 14 32bit and the […]

Bash commands to combine files

Suppose that you want to combine two (or more) files, containing for example a series of data. There are, actually, two ways to do it in bash: $ paste temp1 temp2 > temp which adds the contents of the two files horizontally, like columns, and $ cat temp1 temp2 > temp which adds the contents […]

Changing passwords and keyring

After updating my Fedora 14 login password I was about to use the Empathy messaging client but this “Unlock Login Keyring” dialog box was keeping opening without accepting the new or older passwords… So, while useful it seemed irritating not to be able to use the system with any kind of password working. Searching a […]