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| author | Franklin Schmidt <fschmidt@gmail.com> |
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| date | Thu, 09 Oct 2025 16:56:36 -0600 |
| parents | |
| children | 9134d56639ae |
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| 1 <!doctype html> | |
| 2 <html lang="en"> | |
| 3 <head> | |
| 4 <script src="/site.js"></script> | |
| 5 <script> head() </script> | |
| 6 <title>Arkian - Bash</title> | |
| 7 <script> | |
| 8 'use strict'; | |
| 9 | |
| 10 let content = { | |
| 11 intro: { | |
| 12 title: 'Introduction', | |
| 13 content: `\ | |
| 14 <p>I really don't want to write this tutorial, but all the existing Bash tutorials are so horrible that I have no choice. I looked at books, websites, and YouTube - all horrible. They don't start with the basics. They include all kinds of useless junk. And they don't explain core concepts. So I have no choice but to write this for my <a href="learn.html#bash">Learn Reactionary Programming</a> Bash lesson.</p> | |
| 15 | |
| 16 <p><a href="bash.html">Bash</a> is a <a href="https://en.wikipedia.org/wiki/Unix_shell">shell</a>, one of many, but the one I prefer. I will focus on Mac and Windows. I don't have Linux, and I hate Linux, so I won't discuss it. Most of Bash is the same on Mac and Windows, but where they differ, I will discuss both.</p> | |
| 17 ` , | |
| 18 }, | |
| 19 access: { | |
| 20 title: 'Running Bash', | |
| 21 content: `\ | |
| 22 <p>How you access Bash depends on your operating system. If you are on a Mac then you access Bash through the Mac Terminal which is found in "Applications > Utilities > Terminal.app". Be sure to <a href="https://www.howtogeek.com/444596/how-to-change-the-default-shell-to-bash-in-macos-catalina/">set the default shell to Bash</a>. If you are on Windows then install <a href="https://www.msys2.org/">MSYS2</a>. The default terminal isn't so good, so I suggest <a href="https://www.msys2.org/docs/terminals/#windows-terminal">using the Windows Terminal</a>.</p> | |
| 23 ` , | |
| 24 }, | |
| 25 start: { | |
| 26 title: 'Getting Started', | |
| 27 content: `\ | |
| 28 <p>When I start Bash on my Mac I see:</p> | |
| 29 | |
| 30 <code block> | |
| 31 Last login: Thu Jan 4 23:25:35 on ttys004 | |
| 32 | |
| 33 The default interactive shell is now zsh. | |
| 34 To update your account to use zsh, please run 'chsh -s /bin/zsh'. | |
| 35 For more details, please visit https://support.apple.com/kb/HT208050. | |
| 36 ~ $ | |
| 37 | |
| 38 </code> | |
| 39 | |
| 40 <p>On Windows - MSYS2 I just see:</p> | |
| 41 | |
| 42 <code block> | |
| 43 ~ $ | |
| 44 | |
| 45 </code> | |
| 46 | |
| 47 <p>The line with the <b><code>$</code></b> is the command prompt. The cursor is at the end of it, and if I type, my text will go there. You may have different text before the <b><code>$</code></b> which is okay, but the line should end with <b><code>$</code></b>. If it doesn't, something is wrong.</p> | |
| 48 | |
| 49 <p>Now type "qqq". When I say type "whatever", you should type return/enter at the end. Only when you type return/enter will Bash process what you typed. Now you should see:</p> | |
| 50 | |
| 51 <code block> | |
| 52 ~ $ qqq | |
| 53 -bash: qqq: command not found | |
| 54 ~ $ | |
| 55 </code> | |
| 56 | |
| 57 <p>Bash doesn't know what "qqq" means and says so. Now try the following... Note that you type what is after the <b><code>$</code></b> and Bash should respond as shown.</p> | |
| 58 | |
| 59 <code block> | |
| 60 ~ $ echo hi | |
| 61 hi | |
| 62 ~ $ echo how are you | |
| 63 how are you | |
| 64 ~ $ echo bye | |
| 65 bye | |
| 66 </code> | |
| 67 | |
| 68 <p>The <code>echo</code> command just echoes what comes after. Now press the up-arrow on your keyboard. This should put the previous command where your cursor is. Up-arrow again brings the command before that. Try down-arrow and left-arrow and right-arrow. You can use this to navigate through your command history. The delete key also works for editing lines. And of course you can type. When you press return/enter then Bash will get your edited command and process it.</p> | |
| 69 | |
| 70 <p>When you enter <code>echo how are you</code>, <code>echo</code> is the command. This command has 3 arguments: <code>how</code>, <code>are</code>, and <code>you</code>. Commands and arguments are separated with spaces. It doesn't matter how many spaces, so:</p> | |
| 71 | |
| 72 <code block> | |
| 73 ~ $ echo how are you | |
| 74 how are you | |
| 75 </code> | |
| 76 | |
| 77 <p><code>echo</code> just returns the arguments separated by one space.</p> | |
| 78 | |
| 79 <code block> | |
| 80 ~ $ echo one; echo two | |
| 81 one | |
| 82 two | |
| 83 </code> | |
| 84 | |
| 85 <p>You can put multiple commands on one line separated by a <code>;</code>.</p> | |
| 86 ` , | |
| 87 }, | |
| 88 man: { | |
| 89 title: 'The "man" Command', | |
| 90 content: `\ | |
| 91 <p>Enter:</p> | |
| 92 <code block> | |
| 93 ~ $ man echo | |
| 94 </code> | |
| 95 | |
| 96 <p>You should get something like:</p> | |
| 97 | |
| 98 <code block> | |
| 99 | |
| 100 ECHO(1) BSD General Commands Manual ECHO(1) | |
| 101 | |
| 102 NAME | |
| 103 echo -- write arguments to the standard output | |
| 104 | |
| 105 SYNOPSIS | |
| 106 echo [-n] [string ...] | |
| 107 | |
| 108 DESCRIPTION | |
| 109 The echo utility writes any specified operands, separated by single blank | |
| 110 (' ') characters and followed by a newline ('\\n') character, to the stan- | |
| 111 dard output. | |
| 112 | |
| 113 The following option is available: | |
| 114 | |
| 115 -n Do not print the trailing newline character. This may also be | |
| 116 achieved by appending '\\c' to the end of the string, as is done by | |
| 117 iBCS2 compatible systems. Note that this option as well as the | |
| 118 effect of '\\c' are implementation-defined in IEEE Std 1003.1-2001 | |
| 119 (''POSIX.1'') as amended by Cor. 1-2002. Applications aiming for | |
| 120 maximum portability are strongly encouraged to use printf(1) to | |
| 121 suppress the newline character. | |
| 122 : | |
| 123 </code> | |
| 124 | |
| 125 <p>But if you are on Windows, you may not have <code>man</code> installed. In that case, do:</p> | |
| 126 | |
| 127 <code block> | |
| 128 ~ $ pacman -S man-db | |
| 129 </code> | |
| 130 | |
| 131 <p>to install <code>man</code> as described <a href="https://packages.msys2.org/package/man-db">here</a> and then try <code>man echo</code> again.</p> | |
| 132 | |
| 133 <p>The <code>man</code> command shows documentation of commands. Unfortunately it has a silly user interface based on memorizing keys, so I will just tell you the few keys you need. Down-arrow and up-arrow move down and up by one line. The space key moves down by one page. And most importantly, typing "q" quits and takes you back to Bash. You just have to memorize this.</p> | |
| 134 | |
| 135 <p>Now try entering <code>man man</code>. You don't need all the stuff shown, but you can see what a complicated man page looks like. You can use <code>man</code> to get the documentation of other commands as I discuss them.</p> | |
| 136 ` , | |
| 137 }, | |
| 138 dirs: { | |
| 139 title: 'Directories', | |
| 140 content: `\ | |
| 141 <p>You should be familiar with Mac Finder or Windows File Explorer, and you should know from this that directories (also called "folders") are organized into a tree.</p> | |
| 142 | |
| 143 <p>On Mac:</p> | |
| 144 | |
| 145 <code block> | |
| 146 ~ $ pwd | |
| 147 /Users/fschmidt | |
| 148 ~ $ open . | |
| 149 ~ $ | |
| 150 </code> | |
| 151 | |
| 152 <p>On Windows:</p> | |
| 153 | |
| 154 <code block> | |
| 155 ~ $ pwd | |
| 156 /home/fschmidt | |
| 157 ~ $ explorer . | |
| 158 ~ $ | |
| 159 </code> | |
| 160 | |
| 161 <p>When using Bash, you are always in some directory, called the current directory or the working directory. <code>pwd</code> shows you the full path to this directory. Do <code>man pwd</code> for details. <code>open .</code> should open the Mac Finder for the current directory, and <code>explorer .</code> should open the Windows File Explorer for the current directory.<p> | |
| 162 | |
| 163 <p>Continuing on my Mac:</p> | |
| 164 | |
| 165 <code block> | |
| 166 ~ $ mkdir learn | |
| 167 ~ $ cd learn | |
| 168 ~/learn $ pwd | |
| 169 /Users/fschmidt/learn | |
| 170 </code> | |
| 171 | |
| 172 <p><code>mkdir</code> makes a directory in the current directory. You should be able to see the created directory in Mac Finder or Windows File Explorer. <code>cd</code> stands for "change directory". This changes the current directory. <code>cd</code> is a built-in command (built into Bash), and <code>man</code> isn't useful with built-in commands, so instead of <code>man cd</code>, try <code>help cd</code>. Continuing...</p> | |
| 173 | |
| 174 <code block> | |
| 175 ~/learn $ pwd | |
| 176 /Users/fschmidt/learn | |
| 177 ~/learn $ ls | |
| 178 ~/learn $ touch file1 | |
| 179 ~/learn $ ls | |
| 180 file1 | |
| 181 ~/learn $ touch file2 | |
| 182 ~/learn $ touch file3 | |
| 183 ~/learn $ ls | |
| 184 file1 file2 file3 | |
| 185 ~/learn $ mkdir dir1 | |
| 186 ~/learn $ ls | |
| 187 dir1 file1 file2 file3 | |
| 188 ~/learn $ ls -F | |
| 189 dir1/ file1 file2 file3 | |
| 190 ~/learn $ ls -a | |
| 191 . .. dir1 file1 file2 file3 | |
| 192 ~/learn $ ls -a -F | |
| 193 ./ ../ dir1/ file1 file2 file3 | |
| 194 ~/learn $ ls -aF | |
| 195 ./ ../ dir1/ file1 file2 file3 | |
| 196 </code> | |
| 197 | |
| 198 <p><code>ls</code> lists files and <code>touch</code> creates an empty file. Arguments that start with "-" are options. Do <code>man ls</code> to see what the options I used do. <code>-F</code> appends a "/" to directories, and <code>-a</code> shows files starting with "." which are usually hidden. Options can be combined.</p> | |
| 199 | |
| 200 <code block> | |
| 201 ~/learn $ ls file1 | |
| 202 file1 | |
| 203 ~/learn $ ls qqq | |
| 204 ls: qqq: No such file or directory | |
| 205 ~/learn $ ls file1 qqq file2 | |
| 206 ls: qqq: No such file or directory | |
| 207 file1 file2 | |
| 208 ~/learn $ ls dir1 | |
| 209 ~/learn $ touch dir1/d1file | |
| 210 ~/learn $ ls dir1 | |
| 211 d1file | |
| 212 ~/learn $ ls -d dir1 | |
| 213 dir1 | |
| 214 ~/learn $ ls file1 file2 dir1 | |
| 215 file1 file2 | |
| 216 | |
| 217 dir1: | |
| 218 d1file | |
| 219 ~/learn $ ls -d file1 file2 dir1 | |
| 220 dir1 file1 file2 | |
| 221 ~/learn $ ls -dF file1 file2 dir1 | |
| 222 dir1/ file1 file2 | |
| 223 </code> | |
| 224 | |
| 225 <p>Without file arguments, <code>ls</code> lists files in the current directory. With file arguments, it lists those files if they exist. If the file is a directory, it will list what is in the directory unless the <code>-d</code> option is used.</p> | |
| 226 | |
| 227 <code block> | |
| 228 ~/learn $ ls | |
| 229 dir1 file1 file2 file3 | |
| 230 ~/learn $ ls . | |
| 231 dir1 file1 file2 file3 | |
| 232 ~/learn $ ls -d . | |
| 233 . | |
| 234 ~/learn $ ls -dF . | |
| 235 ./ | |
| 236 ~/learn $ ls ./file1 | |
| 237 ./file1 | |
| 238 ~/learn $ ls dir1 | |
| 239 d1file | |
| 240 ~/learn $ ls ./dir1 | |
| 241 d1file | |
| 242 ~/learn $ pwd | |
| 243 /Users/fschmidt/learn | |
| 244 ~/learn $ cd . | |
| 245 ~/learn $ pwd | |
| 246 /Users/fschmidt/learn | |
| 247 </code> | |
| 248 | |
| 249 <p><code>.</code> is the current directory.</p> | |
| 250 | |
| 251 <code block> | |
| 252 ~/learn $ pwd | |
| 253 /Users/fschmidt/learn | |
| 254 ~/learn $ cd dir1 | |
| 255 ~/learn/dir1 $ pwd | |
| 256 /Users/fschmidt/learn/dir1 | |
| 257 ~/learn/dir1 $ ls . | |
| 258 d1file | |
| 259 ~/learn/dir1 $ ls .. | |
| 260 dir1 file1 file2 file3 | |
| 261 ~/learn/dir1 $ cd .. | |
| 262 ~/learn $ pwd | |
| 263 /Users/fschmidt/learn | |
| 264 ~/learn $ cd dir1 | |
| 265 ~/learn/dir1 $ pwd | |
| 266 /Users/fschmidt/learn/dir1 | |
| 267 ~/learn/dir1 $ cd ../.. | |
| 268 ~ $ pwd | |
| 269 /Users/fschmidt | |
| 270 ~ $ cd learn | |
| 271 ~/learn $ pwd | |
| 272 /Users/fschmidt/learn | |
| 273 </code> | |
| 274 | |
| 275 <p><code>..</code> is the parent directory.</p> | |
| 276 | |
| 277 <code block> | |
| 278 ~/learn $ echo * | |
| 279 dir1 file1 file2 file3 | |
| 280 ~/learn $ echo d* | |
| 281 dir1 | |
| 282 ~/learn $ echo f* | |
| 283 file1 file2 file3 | |
| 284 ~/learn $ echo *1 | |
| 285 dir1 file1 | |
| 286 ~/learn $ echo dir1/* | |
| 287 dir1/d1file | |
| 288 ~/learn $ echo */* | |
| 289 dir1/d1file | |
| 290 ~/learn $ echo qqq* | |
| 291 qqq* | |
| 292 </code> | |
| 293 | |
| 294 <p><code>*</code> does wildcard matching of files. It is important to understand that Bash does the wildcard matching and then passes the resulting arguments to the command. <code>echo</code> never sees the "*" unless there is no match.</p> | |
| 295 | |
| 296 <code block> | |
| 297 ~/learn $ ls * | |
| 298 file1 file2 file3 | |
| 299 | |
| 300 dir1: | |
| 301 d1file | |
| 302 ~/learn $ ls -dF * | |
| 303 dir1/ file1 file2 file3 | |
| 304 ~/learn $ ls -dF d* | |
| 305 dir1/ | |
| 306 ~/learn $ ls -dF f* | |
| 307 file1 file2 file3 | |
| 308 ~/learn $ ls -dF *1 | |
| 309 dir1/ file1 | |
| 310 ~/learn $ ls dir1/* | |
| 311 dir1/d1file | |
| 312 ~/learn $ ls */* | |
| 313 dir1/d1file | |
| 314 ~/learn $ ls -dF qqq* | |
| 315 ls: qqq*: No such file or directory | |
| 316 </code> | |
| 317 | |
| 318 <p>Should be self-explanatory.</p> | |
| 319 | |
| 320 <code block> | |
| 321 ~/learn $ pwd | |
| 322 /Users/fschmidt/learn | |
| 323 ~/learn $ cd ~ | |
| 324 ~ $ pwd | |
| 325 /Users/fschmidt | |
| 326 ~ $ cd learn/dir1 | |
| 327 ~/learn/dir1 $ pwd | |
| 328 /Users/fschmidt/learn/dir1 | |
| 329 ~/learn/dir1 $ cd | |
| 330 ~ $ pwd | |
| 331 /Users/fschmidt | |
| 332 ~ $ cd ~/learn | |
| 333 ~/learn $ pwd | |
| 334 /Users/fschmidt/learn | |
| 335 ~/learn $ echo ~ | |
| 336 /Users/fschmidt | |
| 337 ~/learn $ echo . | |
| 338 . | |
| 339 ~/learn $ echo .. | |
| 340 .. | |
| 341 </code> | |
| 342 | |
| 343 <p><code>~</code> means your home directory. <code>cd</code> without arguments is the same as <code>cd ~</code>. <code>~</code> is expanded into your home directory by Bash.</p> | |
| 344 | |
| 345 <code block> | |
| 346 ~/learn $ ls -ltF | |
| 347 total 0 | |
| 348 drwxr-xr-x 3 fschmidt staff 96 Jan 5 02:33 dir1/ | |
| 349 -rw-r--r-- 1 fschmidt staff 0 Jan 5 02:21 file3 | |
| 350 -rw-r--r-- 1 fschmidt staff 0 Jan 5 02:21 file2 | |
| 351 -rw-r--r-- 1 fschmidt staff 0 Jan 5 02:21 file1 | |
| 352 </code> | |
| 353 | |
| 354 <p><code>-l</code> gives you this ugly techy format. You get the date that the file was last modified. Before the date is the file size. <code>-t</code> sorts by date descending.</p> | |
| 355 | |
| 356 <p>Lastly I will describe autocompletion. I type <code>echo d</code> without enter/return but instead then press the tab key. It autocompletes to <code>echo dir1/</code>. I press tab again and it autocompletes to <code>echo dir1/d1file</code>. Pressing tab while entering a file or directory makes Bash try to autocomplete using matching file names. If I enter <code>echo f</code> and press tab, I get <code>echo file</code>. It doesn't know which to choose next. Another tab just beeps. And another tab shows me the options like this:</p> | |
| 357 | |
| 358 <code block> | |
| 359 ~/learn $ echo file | |
| 360 file1 file2 file3 | |
| 361 ~/learn $ echo file | |
| 362 </code> | |
| 363 | |
| 364 <p>In general, you can press tab anytime while entering a file name and see what happens. Autocompletion saves a lot of typing.</p> | |
| 365 ` , | |
| 366 }, | |
| 367 files: { | |
| 368 title: 'Working with Files', | |
| 369 content: `\ | |
| 370 <code block> | |
| 371 ~/learn $ ls -F | |
| 372 dir1/ file1 file2 file3 | |
| 373 ~/learn $ cp file1 copied | |
| 374 ~/learn $ ls -F | |
| 375 copied dir1/ file1 file2 file3 | |
| 376 ~/learn $ mv copied moved | |
| 377 ~/learn $ ls -F | |
| 378 dir1/ file1 file2 file3 moved | |
| 379 ~/learn $ rm moved | |
| 380 ~/learn $ ls -F | |
| 381 dir1/ file1 file2 file3 | |
| 382 </code> | |
| 383 | |
| 384 <p><code>cp</code> copies files or directories. <code>mv</code> moves files or directories. <code>rm</code> removes files or directories. See the <code>man</code> pages of these commands for details.</p> | |
| 385 | |
| 386 <code block> | |
| 387 ~/learn $ ls -F | |
| 388 dir1/ file1 file2 file3 | |
| 389 ~/learn $ mkdir dir2 | |
| 390 ~/learn $ touch dir2/d2file | |
| 391 ~/learn $ ls -F | |
| 392 dir1/ dir2/ file1 file2 file3 | |
| 393 ~/learn $ ls dir2 | |
| 394 d2file | |
| 395 ~/learn $ rm dir2 | |
| 396 rm: dir2: is a directory | |
| 397 ~/learn $ rm -d dir2 | |
| 398 rm: dir2: Directory not empty | |
| 399 ~/learn $ rm dir2/d2file | |
| 400 ~/learn $ rm -d dir2 | |
| 401 ~/learn $ ls -F | |
| 402 dir1/ file1 file2 file3 | |
| 403 </code> | |
| 404 | |
| 405 <code block> | |
| 406 ~/learn $ ls -F | |
| 407 dir1/ file1 file2 file3 | |
| 408 ~/learn $ mkdir dir2 | |
| 409 ~/learn $ touch dir2/d2file | |
| 410 ~/learn $ ls -F | |
| 411 dir1/ dir2/ file1 file2 file3 | |
| 412 ~/learn $ rm -r dir2 | |
| 413 ~/learn $ ls -F | |
| 414 dir1/ file1 file2 file3 | |
| 415 </code> | |
| 416 | |
| 417 <code block> | |
| 418 ~/learn $ ls -F | |
| 419 dir1/ file1 file2 file3 | |
| 420 ~/learn $ cp dir1 dir2 | |
| 421 cp: dir1 is a directory (not copied). | |
| 422 ~/learn $ cp -r dir1 dir2 | |
| 423 ~/learn $ ls -F | |
| 424 dir1/ dir2/ file1 file2 file3 | |
| 425 ~/learn $ ls dir2 | |
| 426 d1file | |
| 427 ~/learn $ cp f* dir2 | |
| 428 ~/learn $ ls dir2 | |
| 429 d1file file1 file2 file3 | |
| 430 ~/learn $ rm -r dir2 | |
| 431 ~/learn $ ls -F | |
| 432 dir1/ file1 file2 file3 | |
| 433 </code> | |
| 434 | |
| 435 <code block> | |
| 436 ~/learn $ ls -F | |
| 437 dir1/ file1 file2 file3 | |
| 438 ~/learn $ mkdir dir2 | |
| 439 ~/learn $ cp -r dir1 dir2 | |
| 440 ~/learn $ ls -F dir2 | |
| 441 dir1/ | |
| 442 ~/learn $ ls -F dir2/dir1 | |
| 443 d1file | |
| 444 ~/learn $ rm -r dir2 | |
| 445 ~/learn $ ls -F | |
| 446 dir1/ file1 file2 file3 | |
| 447 </code> | |
| 448 | |
| 449 <p>I could explain all this, but I won't. You should learn to understand commands and their options using <code>man</code> and by playing with them. Don't continue until you completely understand the above.</p> | |
| 450 ` , | |
| 451 }, | |
| 452 quote: { | |
| 453 title: 'Quoting', | |
| 454 content: `\ | |
| 455 <code block> | |
| 456 ~/learn $ echo a b | |
| 457 a b | |
| 458 ~/learn $ echo "a b" | |
| 459 a b | |
| 460 ~/learn $ echo 'a b' | |
| 461 a b | |
| 462 ~/learn $ echo "a b" c | |
| 463 a b c | |
| 464 </code> | |
| 465 | |
| 466 <p>Bash treats text in quotes as one argument. So in <code>echo a b</code>, <code>echo</code> has two arguments: "a" and "b". In <code>echo "a b"</code>, <code>echo</code> has one argument: "<span pre>a b</span>". In <code>echo 'a b'</code>, <code>echo</code> has one argument: "<span pre>a b</span>". In <code>echo "a b" c</code>, <code>echo</code> has two arguments: "<span pre>a b</span>" and "c".</p> | |
| 467 | |
| 468 <code block> | |
| 469 ~/learn $ echo a\\ \\ \\ b | |
| 470 a b | |
| 471 </code> | |
| 472 | |
| 473 <p>Outside of quotes, <code>\\ </code> is not treated as a separator, but rather is treated as a space character that is part of the argument.</p> | |
| 474 | |
| 475 <code block> | |
| 476 ~/learn $ echo file* | |
| 477 file1 file2 file3 | |
| 478 ~/learn $ echo "file*" | |
| 479 file* | |
| 480 ~/learn $ echo 'file*' | |
| 481 file* | |
| 482 </code> | |
| 483 | |
| 484 <p>Quotes prevent wildcard expansion.</p> | |
| 485 ` , | |
| 486 }, | |
| 487 vars: { | |
| 488 title: 'Variables', | |
| 489 content: `\ | |
| 490 <code block> | |
| 491 ~/learn $ echo $X | |
| 492 | |
| 493 ~/learn $ X="some text" | |
| 494 ~/learn $ echo $X | |
| 495 some text | |
| 496 ~/learn $ echo "X is: $X" | |
| 497 X is: some text | |
| 498 ~/learn $ echo 'X is: $X' | |
| 499 X is: $X | |
| 500 ~/learn $ X="$X and more" | |
| 501 ~/learn $ echo $X | |
| 502 some text and more | |
| 503 </code> | |
| 504 | |
| 505 <p>Here <code>X</code> is a variable. You get its value with <code>$X</code>. This also works inside double-quotes but not inside single-quotes.</p> | |
| 506 | |
| 507 <p>There are special variables called environment variables that are used by Bash.</p> | |
| 508 | |
| 509 <code block> | |
| 510 ~/learn $ echo $PATH | |
| 511 /usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Users/fschmidt/Dropbox/bin:/Users/fschmidt/hg/luan/scripts:/usr/local/opt/postgresql@9.5/bin | |
| 512 ~/learn $ which ls | |
| 513 /bin/ls | |
| 514 ~/learn $ cd /bin | |
| 515 /bin $ pwd | |
| 516 /bin | |
| 517 /bin $ ls | |
| 518 [ dd launchctl pwd test | |
| 519 bash df link rm unlink | |
| 520 cat echo ln rmdir wait4path | |
| 521 chmod ed ls sh zsh | |
| 522 cp expr mkdir sleep | |
| 523 csh hostname mv stty | |
| 524 dash kill pax sync | |
| 525 date ksh ps tcsh | |
| 526 /bin $ ls -F | |
| 527 [* dd* launchctl* pwd* test* | |
| 528 bash* df* link* rm* unlink* | |
| 529 cat* echo* ln* rmdir* wait4path* | |
| 530 chmod* ed* ls* sh* zsh* | |
| 531 cp* expr* mkdir* sleep* | |
| 532 csh* hostname* mv* stty* | |
| 533 dash* kill* pax* sync* | |
| 534 date* ksh* ps* tcsh* | |
| 535 /bin $ cd ~/learn | |
| 536 ~/learn $ | |
| 537 </code> | |
| 538 | |
| 539 <p><code>PATH</code> is an environment variable containing a list of directories separated by <code>:</code> that are searched for commands by Bash. The <code>which</code> command shows the full path to a command. <code>ls -F</code> appends a <code>*</code> to executable files.</p> | |
| 540 | |
| 541 <code block> | |
| 542 ~/learn $ subl file1 | |
| 543 -bash: subl: command not found | |
| 544 ~/learn $ "/Applications/Sublime Text.app/Contents/SharedSupport/bin/subl" file1 | |
| 545 ~/learn $ PATH="$PATH:/Applications/Sublime Text.app/Contents/SharedSupport/bin" | |
| 546 ~/learn $ echo $PATH | |
| 547 /usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Users/fschmidt/Dropbox/bin:/Users/fschmidt/hg/luan/scripts:/usr/local/opt/postgresql@9.5/bin:/Applications/Sublime Text.app/Contents/SharedSupport/bin | |
| 548 ~/learn $ subl file1 | |
| 549 ~/learn $ | |
| 550 </code> | |
| 551 | |
| 552 <p>Here I edit the file <code>file1</code> with <a href="learn.html#editor">Sublime Text</a>, first by using the full path, and then by adding the directory to <code>PATH</code> so that Bash can find <code>subl</code>.</p> | |
| 553 | |
| 554 <p>I have Microsoft Word on Windows. From the Windows Command Prompt (not Bash):</p> | |
| 555 | |
| 556 <code block> | |
| 557 C:\\Users\\fschmidt>winword | |
| 558 | |
| 559 C:\\Users\\fschmidt>where winword | |
| 560 C:\\Program Files\\Microsoft Office\\root\\Office16\\WINWORD.EXE | |
| 561 </code> | |
| 562 | |
| 563 <p><code>winword</code> runs Microsoft Word. The Command Prompt <code>where</code> command is like the Bash <code>which</code> command. So now on MSYS2:</p> | |
| 564 | |
| 565 <code block> | |
| 566 ~ $ winword | |
| 567 bash: winword: command not found | |
| 568 ~ $ echo $PATH | |
| 569 /usr/local/bin:/usr/bin:/bin:/opt/bin:/c/Windows/System32:/c/Windows:/c/Windows/System32/Wbem:/c/Windows/System32/WindowsPowerShell/v1.0/:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/c/Program Files/TortoiseHg:/c/Program Files/Java/jdk1.8.0_202/bin | |
| 570 ~ $ PATH="$PATH:/c/Program Files/Microsoft Office/root/Office16" | |
| 571 ~ $ echo $PATH | |
| 572 /usr/local/bin:/usr/bin:/bin:/opt/bin:/c/Windows/System32:/c/Windows:/c/Windows/System32/Wbem:/c/Windows/System32/WindowsPowerShell/v1.0/:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/c/Program Files/TortoiseHg:/c/Program Files/Java/jdk1.8.0_202/bin:/c/Program Files/Microsoft Office/root/Office16 | |
| 573 ~ $ winword | |
| 574 ~ $ | |
| 575 </code> | |
| 576 | |
| 577 <p>Returning to the Mac, there is another way to run applications found in Finder's "Applications" simply as applications instead of as commands.</p> | |
| 578 | |
| 579 <code block> | |
| 580 ~/learn $ open -a 'Sublime Text' file1 | |
| 581 </code> | |
| 582 | |
| 583 <p>Another useful environment variable is <code>PS1</code> which controls the command prompt. I already have this set up, but if I didn't:</p> | |
| 584 | |
| 585 <code block> | |
| 586 Franklins-MacBook-Pro:learn fschmidt$ echo $PS1 | |
| 587 \\h:\\W \\u\\$ | |
| 588 Franklins-MacBook-Pro:learn fschmidt$ PS1="\\w $ " | |
| 589 ~/learn $ echo $PS1 | |
| 590 \\w $ | |
| 591 ~/learn $ | |
| 592 </code> | |
| 593 | |
| 594 <p>Google "bash PS1" for more info.</p> | |
| 595 ` , | |
| 596 }, | |
| 597 bash_profile: { | |
| 598 title: '.bash_profile', | |
| 599 content: `\ | |
| 600 <code block> | |
| 601 ~/learn $ cd | |
| 602 ~ $ ls .bash_profile | |
| 603 .bash_profile | |
| 604 </code> | |
| 605 | |
| 606 <p>If <code>.bash_profile</code> isn't found then do <code>touch .bash_profile</code> to create it. This file contains Bash commands that are run when Bash starts. If you already have this file, it is likely to contain comments that start with <code>#</code>. Comments are ignored like this:</p> | |
| 607 | |
| 608 <code block> | |
| 609 ~ $ # comment line, does nothing | |
| 610 ~ $ echo whatever # end of line comment | |
| 611 whatever | |
| 612 ~ $ | |
| 613 </code> | |
| 614 | |
| 615 <p>To edit <code>.bash_profile</code> on a Mac, you can do:</p> | |
| 616 | |
| 617 <code block> | |
| 618 ~ $ open -a 'Sublime Text' .bash_profile | |
| 619 </code> | |
| 620 | |
| 621 <p>To edit <code>.bash_profile</code> on Windows, you can do:</p> | |
| 622 | |
| 623 <code block> | |
| 624 ~ $ notepad .bash_profile | |
| 625 </code> | |
| 626 | |
| 627 <p>Now try adding this line to <code>.bash_profile</code>:</p> | |
| 628 | |
| 629 <code block> | |
| 630 echo hello there | |
| 631 </code> | |
| 632 | |
| 633 <p>Now when you open a new Bash terminal, you should see "hello there". <code>.bash_profile</code> runs when Bash is started by opening a new Bash terminal.</p> | |
| 634 | |
| 635 <p>I set <code>PS1</code> and <code>PATH</code> in <code>.bash_profile</code> to have the command prompt I want, and access to the commands that I want. I suggest that you make the <a href="https://www.sublimetext.com/docs/command_line.html">Sublime Text command</a> <code>subl</code> available in <code>PATH</code>.</p> | |
| 636 ` , | |
| 637 }, | |
| 638 find: { | |
| 639 title: 'The "find" Command', | |
| 640 content: `\ | |
| 641 <code block> | |
| 642 ~/learn $ find . | |
| 643 . | |
| 644 ./file3 | |
| 645 ./file2 | |
| 646 ./file1 | |
| 647 ./dir1 | |
| 648 ./dir1/d1file | |
| 649 ~/learn $ find . -name 'file*' | |
| 650 ./file3 | |
| 651 ./file2 | |
| 652 ./file1 | |
| 653 ~/learn $ find . -name '*file' | |
| 654 ./dir1/d1file | |
| 655 ~/learn $ find . -name 'd*' | |
| 656 ./dir1 | |
| 657 ./dir1/d1file | |
| 658 ~/learn $ find . -name '*1' -or -name '*2' | |
| 659 ./file2 | |
| 660 ./file1 | |
| 661 ./dir1 | |
| 662 </code> | |
| 663 | |
| 664 <p><code>find</code> recursively searches for files in a directory tree. Note that in this case the <code>*</code> wildcard matching is not being done by Bash, it is being done by <code>find</code>. <code>find</code> has many options for searching for files and acting on them, see <code>man find</code>.</p> | |
| 665 ` , | |
| 666 }, | |
| 667 io: { | |
| 668 title: 'Input and Output', | |
| 669 content: `\ | |
| 670 <code block> | |
| 671 ~/learn $ echo 'this is a test' >test.txt | |
| 672 ~/learn $ ls -F | |
| 673 dir1/ file1 file2 file3 test.txt | |
| 674 ~/learn $ cat test.txt | |
| 675 this is a test | |
| 676 ~/learn $ echo 'this is another test' >test.txt | |
| 677 ~/learn $ cat test.txt | |
| 678 this is another test | |
| 679 ~/learn $ echo 'another line' >>test.txt | |
| 680 ~/learn $ cat test.txt | |
| 681 this is another test | |
| 682 another line | |
| 683 ~/learn $ cat <test.txt | |
| 684 this is another test | |
| 685 another line | |
| 686 ~/learn $ cat <<End >test.txt | |
| 687 > I am typing this | |
| 688 > and this | |
| 689 > End | |
| 690 ~/learn $ cat test.txt | |
| 691 I am typing this | |
| 692 and this | |
| 693 ~/learn $ (echo one; echo two) >test.txt | |
| 694 ~/learn $ cat test.txt | |
| 695 one | |
| 696 two | |
| 697 </code> | |
| 698 | |
| 699 <p>All programs have standard input, standard output, and standard error. Programs write normal output to standard output and error messages to standard error. By default, standard input comes from the terminal, and standard output and standard error go to the terminal, but this can be changed. <code>>file</code> sends standard output to <code>file</code>. <code>>>file</code> appends standard output to <code>file</code>. <code><file</code> reads standard input from <code>file</code>. <code><<whatever</code> reads standard input from the text that follows until a line with just <code>whatever</code>. Commands can be combined between <code>(</code> and <code>)</code>. Be sure to <code>man cat</code> to understand how <code>cat</code> works.</p> | |
| 700 | |
| 701 <code block> | |
| 702 ~/learn $ ls >ls.txt | |
| 703 ~/learn $ cat ls.txt | |
| 704 dir1 | |
| 705 file1 | |
| 706 file2 | |
| 707 file3 | |
| 708 ls.txt | |
| 709 test.txt | |
| 710 ~/learn $ ls -d f* q* >ls.txt | |
| 711 ls: q*: No such file or directory | |
| 712 ~/learn $ cat ls.txt | |
| 713 file1 | |
| 714 file2 | |
| 715 file3 | |
| 716 ~/learn $ ls -d f* q* 2>ls.txt | |
| 717 file1 file2 file3 | |
| 718 ~/learn $ cat ls.txt | |
| 719 ls: q*: No such file or directory | |
| 720 ~/learn $ ls -d f* q* | tee ls.txt | |
| 721 ls: q*: No such file or directory | |
| 722 file1 | |
| 723 file2 | |
| 724 file3 | |
| 725 ~/learn $ cat ls.txt | |
| 726 file1 | |
| 727 file2 | |
| 728 file3 | |
| 729 ~/learn $ ls -d f* q* 2>&1 | tee ls.txt | |
| 730 ls: q*: No such file or directory | |
| 731 file1 | |
| 732 file2 | |
| 733 file3 | |
| 734 ~/learn $ cat ls.txt | |
| 735 ls: q*: No such file or directory | |
| 736 file1 | |
| 737 file2 | |
| 738 file3 | |
| 739 </code> | |
| 740 | |
| 741 <p><code>2>file</code> sends standard error to <code>file</code>. <code>|</code> sends standard output of the previous command to standard input of the following command. <code>2>&1</code> sends standard error to standard output. <code>tee file</code> reads standard input and then writes it to both standard output and to <code>file</code>.</p> | |
| 742 | |
| 743 <code block> | |
| 744 ~/learn $ find . -type f | wc -l | |
| 745 6 | |
| 746 </code> | |
| 747 | |
| 748 <p>There are 6 files in <code>learn</code>. Use <code>man</code> to figure out how this works.</p> | |
| 749 ` , | |
| 750 }, | |
| 751 ctrl: { | |
| 752 title: 'Control Keys', | |
| 753 content: `\ | |
| 754 <code block> | |
| 755 ~/learn $ sleep 3 | |
| 756 ~/learn $ sleep 30 | |
| 757 ^C | |
| 758 ~/learn $ | |
| 759 </code> | |
| 760 | |
| 761 <p><code>sleep 3</code> sleeps for 3 seconds, meaning it does nothing for 3 seconds. I waited 3 seconds for this command to finish. Then I ran <code>sleep 30</code> which would sleep for 30 seconds, but I lost my patience and pressed control+c which interrupts the program and breaks out of it. You can try control+c if you ever get stuck waiting for a command to finish.</p> | |
| 762 | |
| 763 <code block> | |
| 764 ~/learn $ wc | |
| 765 I am typing this | |
| 766 and this | |
| 767 now I will end my input with control+d | |
| 768 3 14 65 | |
| 769 ~/learn $ wc | |
| 770 this time I will use control+c to break out | |
| 771 ^C | |
| 772 ~/learn $ | |
| 773 </code> | |
| 774 | |
| 775 <p>Control+d means end of input.</p> | |
| 776 ` , | |
| 777 }, | |
| 778 subst: { | |
| 779 title: 'Command Substitution', | |
| 780 content: `\ | |
| 781 <code block> | |
| 782 ~/learn $ echo I am in $(pwd) | |
| 783 I am in /Users/fschmidt/learn | |
| 784 ~/learn $ echo this directory contains: $(ls) | |
| 785 this directory contains: dir1 file1 file2 file3 ls.txt test.txt | |
| 786 ~/learn $ echo this directory contains $(ls | wc -l) files | |
| 787 this directory contains 6 files | |
| 788 </code> | |
| 789 | |
| 790 <p><code>cmd $(commands)</code> will use the output of <code>commands</code> as argument text for <code>cmd</code>.</p> | |
| 791 | |
| 792 <code block> | |
| 793 ~/learn $ cat $(find . -type f) | wc -c | |
| 794 86 | |
| 795 </code> | |
| 796 | |
| 797 <p>The files in <code>learn</code> contain a total of 86 bytes. Use <code>man</code> to figure out how this works.</p> | |
| 798 ` , | |
| 799 }, | |
| 800 ampersand: { | |
| 801 title: 'Ampersand', | |
| 802 content: `\ | |
| 803 <code block> | |
| 804 ~/learn $ (sleep 5; echo done) & | |
| 805 [1] 10080 | |
| 806 ~/learn $ echo waiting | |
| 807 waiting | |
| 808 ~/learn $ done | |
| 809 | |
| 810 [1]+ Done ( sleep 5; echo done ) | |
| 811 ~/learn $ | |
| 812 </code> | |
| 813 | |
| 814 <p>Normally Bash waits for a command to complete before showing the command prompt and allowing input. But ending a command line with <code>&</code> tells bash not to wait, but instead to run the command in a separate process. Above in <code>~/learn $ echo waiting</code>, I typed in <code>echo waiting</code>. But in <code>~/learn $ done</code>, I did not type <code>done</code>. Instead this was produced by <code>echo done</code> after 5 seconds. <code>[1] 10080</code> tells me that a process was started and <code>[1]+ Done ( sleep 5; echo done )</code> tells me that the process finished.</p> | |
| 815 | |
| 816 <p>This is useful where you do not want to wait for a command to finish. Consider this on Windows:</p> | |
| 817 | |
| 818 <code block> | |
| 819 ~ $ notepad | |
| 820 </code> | |
| 821 | |
| 822 <p>Here you will not get a command prompt again until you quit Notepad because Bash is waiting for this command to finish. So instead do: | |
| 823 | |
| 824 <code block> | |
| 825 ~ $ notepad & | |
| 826 [1] 2010 | |
| 827 ~ $ | |
| 828 </code> | |
| 829 | |
| 830 <p>Now Notepad will run and you can continue using Bash.</p> | |
| 831 ` , | |
| 832 }, | |
| 833 scripts: { | |
| 834 title: 'Shell Scripts', | |
| 835 content: `\ | |
| 836 <p>Make a file called <code>test.sh</code> containing the following:</p> | |
| 837 | |
| 838 <code block> | |
| 839 echo this is a shell script | |
| 840 </code> | |
| 841 | |
| 842 <p>Now from Bash:</p> | |
| 843 | |
| 844 <code block> | |
| 845 ~/learn $ cat test.sh | |
| 846 echo this is a shell script | |
| 847 ~/learn $ ./test.sh | |
| 848 -bash: ./test.sh: Permission denied | |
| 849 ~/learn $ ls -F test.sh | |
| 850 test.sh | |
| 851 ~/learn $ chmod +x test.sh | |
| 852 ~/learn $ ls -F test.sh | |
| 853 test.sh* | |
| 854 ~/learn $ ./test.sh | |
| 855 this is a shell script | |
| 856 ~/learn $ | |
| 857 </code> | |
| 858 | |
| 859 <p><code>chmod +x file</code> makes <code>file</code> into an executable that can be run. Now I will edit <code>test.sh</code></p> | |
| 860 | |
| 861 <code block> | |
| 862 ~/learn $ # edit test.sh | |
| 863 ~/learn $ cat test.sh | |
| 864 nonsense | |
| 865 echo this is a shell script | |
| 866 ~/learn $ ./test.sh | |
| 867 ./test.sh: line 1: nonsense: command not found | |
| 868 this is a shell script | |
| 869 ~/learn $ # edit test.sh | |
| 870 ~/learn $ cat test.sh | |
| 871 set -e | |
| 872 nonsense | |
| 873 echo this is a shell script | |
| 874 ~/learn $ ./test.sh | |
| 875 ./test.sh: line 2: nonsense: command not found | |
| 876 ~/learn $ | |
| 877 </code> | |
| 878 | |
| 879 <p>By default, scripts continue running after an error. In longer scripts, we want the script to exit after an error. <code>set -e</code> does this, see <code>help set</code>.</p> | |
| 880 | |
| 881 <code block> | |
| 882 ~/learn $ X=some | |
| 883 ~/learn $ echo $X | |
| 884 some | |
| 885 ~/learn $ echo $Xthing | |
| 886 | |
| 887 ~/learn $ echo \${X}thing | |
| 888 something | |
| 889 ~/learn $ # edit test.sh | |
| 890 ~/learn $ cat test.sh | |
| 891 echo "\\$* = $*" | |
| 892 echo "\\$# = $#" | |
| 893 echo "\\$0 = $0" | |
| 894 echo "\\$1 = $1" | |
| 895 echo "\\$2 = $2" | |
| 896 echo "\\$3 = $3" | |
| 897 echo "\\$4 = $4" | |
| 898 echo "\\$14 = $14" | |
| 899 echo "\\\${14} = \$\{14}" | |
| 900 echo "\\$@ = $@" | |
| 901 ./count.sh "$*" | |
| 902 ./count.sh "$@" | |
| 903 ~/learn $ ./test.sh a b "c d" | |
| 904 $* = a b c d | |
| 905 $# = 3 | |
| 906 $0 = ./test.sh | |
| 907 $1 = a | |
| 908 $2 = b | |
| 909 $3 = c d | |
| 910 $4 = | |
| 911 $14 = a4 | |
| 912 \${14} = | |
| 913 $@ = a b c d | |
| 914 1 | |
| 915 3 | |
| 916 ~/learn $ cat count.sh | |
| 917 echo $# | |
| 918 ~/learn $ | |
| 919 </code> | |
| 920 | |
| 921 <p>Bash scripts have special defined variables. The difference between <code>$*</code> and <code>$@</code> is subtle, and you will usually just use <code>$*</code>. <code>$*</code> returns all arguments as one string while <code>$@</code> returns the arguments separately, but this distinction rarely makes any difference.</p> | |
| 922 ` , | |
| 923 }, | |
| 924 vars_and_scripts: { | |
| 925 title: 'Variables and Scripts', | |
| 926 content: `\ | |
| 927 <code block> | |
| 928 ~/learn $ X=value | |
| 929 ~/learn $ echo $X | |
| 930 value | |
| 931 ~/learn $ # edit test.sh | |
| 932 ~/learn $ cat test.sh | |
| 933 echo "\\$X = $X" | |
| 934 ~/learn $ ./test.sh | |
| 935 $X = | |
| 936 ~/learn $ export X | |
| 937 ~/learn $ ./test.sh | |
| 938 $X = value | |
| 939 </code> | |
| 940 | |
| 941 <p>Variables are defined in the current shell. Shell scripts are run in their own shell. So by default, they don't see variables defined in the terminal/parent shell. <code>export var</code> makes <code>var</code> available in descendant processes, meaning available in shell scripts. It is a good idea to do <code>export PATH</code> in <code>.bash_profile</code> so that your PATH is available to your scripts.</p> | |
| 942 | |
| 943 <code block> | |
| 944 ~/learn $ X=terminal | |
| 945 ~/learn $ echo $X | |
| 946 terminal | |
| 947 ~/learn $ # edit test.sh | |
| 948 ~/learn $ cat test.sh | |
| 949 X=script | |
| 950 export X | |
| 951 ~/learn $ ./test.sh | |
| 952 ~/learn $ echo $X | |
| 953 terminal | |
| 954 ~/learn $ . test.sh | |
| 955 ~/learn $ echo $X | |
| 956 script | |
| 957 </code> | |
| 958 | |
| 959 <p>You can export a variable from parent to children but not from children to parent. <code>. script</code> includes the text in the file <code>script</code> in the current shell. In this case, it is not run in a separate shell. This is the only way to have a script set variables in your terminal shell.</p> | |
| 960 | |
| 961 <code block> | |
| 962 ~/learn $ pwd | |
| 963 /Users/fschmidt/learn | |
| 964 ~/learn $ # edit test.sh | |
| 965 ~/learn $ cat test.sh | |
| 966 cd ~ | |
| 967 ~/learn $ ./test.sh | |
| 968 ~/learn $ pwd | |
| 969 /Users/fschmidt/learn | |
| 970 ~/learn $ . test.sh | |
| 971 ~ $ pwd | |
| 972 /Users/fschmidt | |
| 973 ~ $ cd learn | |
| 974 ~/learn $ | |
| 975 </code> | |
| 976 | |
| 977 <p>This illustrates the difference between <code>./script</code> and <code>. script</code>.</p> | |
| 978 ` , | |
| 979 }, | |
| 980 your_scripts: { | |
| 981 title: 'Your Scripts', | |
| 982 content: `\ | |
| 983 <code block> | |
| 984 ~/learn $ echo $PATH | |
| 985 /usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Users/fschmidt/Dropbox/bin:/Users/fschmidt/hg/luan/scripts:/usr/local/opt/postgresql@9.5/bin:/Applications/Sublime Text.app/Contents/SharedSupport/bin | |
| 986 ~/learn $ echo ~/Dropbox/bin | |
| 987 /Users/fschmidt/Dropbox/bin | |
| 988 ~/learn $ ls -F ~/Dropbox/bin/e | |
| 989 /Users/fschmidt/Dropbox/bin/e* | |
| 990 ~/learn $ cat ~/Dropbox/bin/e | |
| 991 open -a 'Sublime Text' $* | |
| 992 ~/learn $ e test.sh | |
| 993 ~/learn $ | |
| 994 </code> | |
| 995 | |
| 996 <p>When you write useful scripts, put them in a directory and add that directory to your PATH. I use <code>~/Dropbox/bin</code> and I have a script named <code>e</code> in that directory for editing files. So <code>e test.sh</code> lets me edit <code>test.sh</code> from the command line.</p> | |
| 997 | |
| 998 <p>Note that Bash will only look in your PATH for scripts unless you give an explicit path to the script.</p> | |
| 999 | |
| 1000 <code block> | |
| 1001 ~/learn $ # edit test.sh | |
| 1002 ~/learn $ cat test.sh | |
| 1003 echo this is a shell script | |
| 1004 ~/learn $ test.sh | |
| 1005 -bash: test.sh: command not found | |
| 1006 ~/learn $ ./test.sh | |
| 1007 this is a shell script | |
| 1008 ~/learn $ | |
| 1009 </code> | |
| 1010 | |
| 1011 <p>Calling <code>test.sh</code> by itself fails because it isn't in the PATH. But <code>./test.sh</code> works because it is an explicit path.</p> | |
| 1012 ` , | |
| 1013 }, | |
| 1014 advanced: { | |
| 1015 title: 'Advanced Scripting', | |
| 1016 content: `\ | |
| 1017 <p>Here is a more advanced script called <code>undocx.sh</code> that unpacks a Word DOCX file.</p> | |
| 1018 | |
| 1019 <code block> | |
| 1020 #!/bin/bash | |
| 1021 | |
| 1022 set -e | |
| 1023 | |
| 1024 if [ $# -ne 1 ]; then | |
| 1025 echo "usage: $0 filename" | |
| 1026 exit 1 | |
| 1027 fi | |
| 1028 | |
| 1029 FILE="$1" | |
| 1030 NEWDIR=$(basename $FILE .docx) | |
| 1031 | |
| 1032 mkdir $NEWDIR | |
| 1033 unzip $FILE -d $NEWDIR | |
| 1034 | |
| 1035 export XMLLINT_INDENT=$'\\t' | |
| 1036 for file in $(find $NEWDIR -name "*.xml" -o -name "*.rels"); do | |
| 1037 mv "$file" temp.xml | |
| 1038 xmllint --format temp.xml >"$file" | |
| 1039 done | |
| 1040 rm temp.xml | |
| 1041 </code> | |
| 1042 | |
| 1043 <p>Bash is a full programming language containing all the usual features. Some commands in my script are well explained by <code>man</code>, but some are not. In particular, the documentation for <code>if</code> and <code>for</code> are poor. In cases like this, I suggest asking ChatGPT like this: | |
| 1044 | |
| 1045 <code block> | |
| 1046 Please explain the Bash "if" statement. | |
| 1047 </code> | |
| 1048 | |
| 1049 <code block> | |
| 1050 Please explain the Bash "for" statement. | |
| 1051 </code> | |
| 1052 | |
| 1053 <p>ChatGPT knows Bash well. I trust ChatGPT to explain details but not to explain core concepts. You can also try Google, but ChatGPT is better than modern programmers.</p> | |
| 1054 ` , | |
| 1055 }, | |
| 1056 conclusion: { | |
| 1057 title: 'Conclusion', | |
| 1058 content: `\ | |
| 1059 <p>At least 90% of your usage of Bash will be simple commands that you enter in the terminal. Try to use Bash as much as possible instead of using the GUI so that you get practice using it. Unless you become system administrator, you won't use advanced scripting much. But with a solid understanding of the core basics, you should be able to figure out how to read or write advanced scripts when needed.</p> | |
| 1060 ` , | |
| 1061 }, | |
| 1062 }; | |
| 1063 </script> | |
| 1064 </head> | |
| 1065 <body> | |
| 1066 <script> header() </script> | |
| 1067 <div content> | |
| 1068 <h1><a href="bash.html">Bash Tutorial</a></h1> | |
| 1069 <hr> | |
| 1070 <h2>Contents</h2> | |
| 1071 <div toc> | |
| 1072 <script> showToc(content) </script> | |
| 1073 </div> | |
| 1074 <hr> | |
| 1075 <script> showContent(content,2) </script> | |
| 1076 </div> | |
| 1077 </body> | |
| 1078 </html> |