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"# LINUX Shell\n",
"\n",
"This time, we will learn very basic things on LINUX. You can find any good references from anywhere, and I will explain very basic things which are essential to follow the course materials.\n",
"\n",
"## Some Jargons\n",
"\n",
"* **directory**: For Windows users, the word \"directory\" may not be familiar. It is similar to \"folder\".\n",
"* **terminal**: Decades ago, there was no \"monitor\" like today. Terminal was used as a tunnel between the computer or calculator and human (thus \"terminal\". In other words, it displays things from computer to people OR gets input from person to computer. Nowadays, terminal means a program which does similar job, but with much powerful functionalities.\n",
"* **shell**: Shell is an application running on terminal, and it interprets what people type to the terminal. Thus it is also called \"command line interpreter\". `bash` is one of such shells. \n",
"* **prompt**: A serial of characters which indicates that the terminal is ready to get command from you. It's `$` on Ubuntu and `>>>` for Python.\n",
"* `ls`: \"List\"\n",
"* `cd`: \"Change Directory\"\n",
"* `cp`: \"Copy\"\n",
"* `mv`: \"Move\"\n",
"* `mkdir`: \"Make Directory\"\n",
"* `pwd`: \"Present Working Directory\", i.e., your present location\n",
"* `chmod`: \"Change Mode\"\n",
"* `rm`: \"Remove\"\n",
"* `~`: The home directory. Type `cd ~` and then `pwd` to see what `~` means.\n",
"\n",
"If you want, you can find manuals from [here](https://ss64.com/bash/)."
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"## Tutorial\n",
"\n",
"Now I will show you how some simple commands work.\n",
"\n",
" aaa@YPB:~/AO_2017$ ls\n",
" 00_Preface-English.ipynb 01_Installation.ipynb 02_Python_Basic.ipynb html\n",
" 00_Preface-Korean.ipynb 01_LINUX_Shell.ipynb 03_Get_the_Taste.ipynb README.md\n",
"\n",
"By default, you may see colors for different types, e.g., gray for normal files and blue for directories. \n",
"\n",
" aaa@YPB:~/AO_2017$ ll\n",
" total 200\n",
" drwxrwxr-x 5 aaa aaa 4096 3 15 03:13 ./\n",
" drwxrwxr-x 5 aaa aaa 4096 3 14 01:18 ../\n",
" -rw-rw-r-- 1 aaa aaa 22660 3 13 23:07 00_Preface-English.ipynb\n",
" -rw-rw-r-- 1 aaa aaa 27503 3 13 15:22 00_Preface-Korean.ipynb\n",
" -rw-rw-r-- 1 aaa aaa 16134 3 13 23:20 01_Installation.ipynb\n",
" -rw-rw-r-- 1 aaa aaa 2184 3 15 03:13 01_LINUX_Shell.ipynb\n",
" -rw-rw-r-- 1 aaa aaa 21730 3 13 23:48 02_Python_Basic.ipynb\n",
" -rw-rw-r-- 1 aaa aaa 81065 3 14 03:19 03_Get_the_Taste.ipynb\n",
" drwxrwxr-x 8 aaa aaa 4096 3 15 02:50 .git/\n",
" drwxrwxr-x 2 aaa aaa 4096 3 14 22:43 html/\n",
" drwxr-xr-x 2 aaa aaa 4096 3 15 02:51 .ipynb_checkpoints/\n",
" -rw-rw-r-- 1 aaa aaa 342 3 14 00:03 README.md\n",
"\n",
"Here, the directory or files start with `.` are the ones which are *hidden*. The first column means the permissions (see some manual for `chmod`). \n",
"\n",
"Let's make a test file:\n",
"\n",
" vi sample.txt\n",
"\n",
"`vi` is a default editor. Hit `i` and type \"hello\". Hit `Esc`, and then colon (`:`). You will see the colon appeared at the bottom. Type \"`wq`\" and hit `Enter`. `wq` means write and quit. Then typing `ls` will show you a new file named \"`sample.txt`\".\n",
"\n",
"\n",
"Now let's move it to a new directory. You can type\n",
"\n",
" mkdir test <--- make directory named \"test\"\n",
" cd test <--- go to that directory\n",
" mv ../sample.txt . <--- move the \"sample.txt\" to here (.)\n",
" pwd <--- print your current location\n",
" ls <--- show file list\n",
" \n",
"You may want to rename or copy the file:\n",
"\n",
" cp sample.txt .. <--- copy sample.txt to the higher directory\n",
" cp sample.txt qq.txt <--- copy sample.txt to the higher directory with a new name \"qq.txt\"\n",
" mv sample.txt pp.txt <--- move sample.txt as pp.txt, i.e., identical to \"rename\"! \n",
" \n",
"How can we remove `pp.txt` and the directory `test`?\n",
"\n",
" rm pp.txt <--- remove pp.txt\n",
" cd .. \n",
" rm -r test <--- remove test directory\n",
" \n",
"As you saw, to delete directory, you need an option \"`-r`\", which means \"recursive\". If you don't do so, you will get an error message \n",
"\n",
" rm test\n",
" rm: cannot remove 'test/': Is a directory\n",
" \n",
" "
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"## Little More\n",
"\n",
"You may frequently need a list of filenames. For example, you want to open FITS files \"abc.fits\", \"def2.fits\", ..., \"zer0.fits\", which have no clue on the naming. One way is to make a text file contains the file names, and load it from Python. Then, you can use for loop to open each file sequentially. \n",
"\n",
" ls *.fits >> list.txt\n",
" \n",
"Here, `*` means \"any string\", i.e., `ls *.fits` will list any file ends with `.fits`. `>>` means \"add to\", or \"append to\". That is, all the output of `ls *.fits` will be added to a file named `list.txt`. If there is no file named `ls *.fits`, it will automatically make it.\n",
" \n",
" ls *.fits > list.txt\n",
" \n",
"Test what happens when you use \"`>`\".\n",
" \n"
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