Bash It Up
ENGR 1213

Some helpful hints for the bash shell follow.

0.script xxxx - captures and extire bash session which you can review later in a file named xxxx

1.pwd - displays current dir 
	evan@ELEMLEY-LINUX:~/Desktop/evdoc/porous_media$ pwd
	/home/evan/Desktop/evdoc/porous_media

2.ls - lists things
	evan@ELEMLEY-LINUX:~/Desktop/evolver$ ls -Alt
	total 4276
	drwxr-xr-x 2 evan evan    4096 2008-02-26 14:14 src
	-rw-r--r-- 1 evan evan 2901023 2008-02-26 14:10 evolver-2.30c.tar.gz
	-rw-r--r-- 1 evan evan 1437981 2008-01-04 06:54 manual230.pdf
	drwxr-xr-x 2 evan evan    4096 2008-01-03 13:11 doc
	-rw-r--r-- 1 evan evan    5495 2008-01-03 11:54 README
	drwxr-xr-x 2 evan evan    4096 2008-01-03 11:38 fe
	-rw-r--r-- 1 evan evan    3581 2005-08-21 12:22 evolver.1

3.chmod - regular mode 

	The format of a symbolic mode is ‘[ugoa...][[+-=][rwxXstugo...]...][,...]’.  Multiple symbolic operations can be
	given, separated by commas.

	u = user, g = group, o = others, a = all
	r = read, w = write, x = execute, X = execute only if the file is a directory or already has execute permission for some user
	+ permissions added, - permissions removed, = these will be the only permissions

		evan@ELEMLEY-LINUX:~/Desktop/evolver$ ls -l manual230.pdf
		-rw-r--r-- 1 evan evan 1437981 2008-01-04 06:54 manual230.pdf

		evan@ELEMLEY-LINUX:~/Desktop/evolver$ chmod u+wx,g+wx,o+w manual230.pdf

		evan@ELEMLEY-LINUX:~/Desktop/evolver$ ls -l manual230.pdf
		-rwxrwxrw- 1 evan evan 1437981 2008-01-04 06:54 manual230.pdf

		evan@ELEMLEY-LINUX:~/Desktop/evolver$ chmod o=r manual230.pdf

		evan@ELEMLEY-LINUX:~/Desktop/evolver$ ls -l manual230.pdf
		-rwxrwxr-- 1 evan evan 1437981 2008-01-04 06:54 manual230.pdf


4.chmod - octal mode (0-7)

	Four digits determine the changes
	First is user or group id (we will not use) - if you submit three values it is assumed you have not submitted this one.
	Second is user (4 = read, 2 = write, 1 = execute)
	Third is group (4 = read, 2 = write, 1 = execute)
	Fourth is others (4 = read, 2 = write, 1 = execute)
	
	If you want more than one permission just add the numbers - e.g. read+write = 4+2 = 6
	read+write+execute = 4+2+1 = 7, read+execute = 4+1 = 5

		evan@ELEMLEY-LINUX:~/Desktop/evolver$ ls -l manual230.pdf
		-rwxrw-rw- 1 evan evan 1437981 2008-01-04 06:54 manual230.pdf
		
		evan@ELEMLEY-LINUX:~/Desktop/evolver$ chmod 644  manual230.pdf

		evan@ELEMLEY-LINUX:~/Desktop/evolver$ ls -l manual230.pdf
		-rw-r--r-- 1 evan evan 1437981 2008-01-04 06:54 manual230.pdf

5.Redirection (>)

To output the results of a single command use the '>' redirection operator to send the results to a file

	evan@ELEMLEY-LINUX:~/Desktop/evolver$ ls -Alt > dirlisting.txt

	evan@ELEMLEY-LINUX:~/Desktop/evolver$ cat dirlisting.txt
	total 4284
	-rw-r--r-- 1 evan evan       0 2008-08-25 11:33 dirlisting.txt
	-rw-r--r-- 1 evan evan    4206 2008-08-25 10:45 test
	drwxr-xr-x 2 evan evan    4096 2008-02-26 14:14 src
	-rw-r--r-- 1 evan evan 2901023 2008-02-26 14:10 evolver-2.30c.tar.gz
	-rw-r--r-- 1 evan evan 1437981 2008-01-04 06:54 manual230.pdf
	drwxr-xr-x 2 evan evan    4096 2008-01-03 13:11 doc
	-rw-r--r-- 1 evan evan    5495 2008-01-03 11:54 README
	drwxr-xr-x 2 evan evan    4096 2008-01-03 11:38 fe
	-rwxr-xr-x 1 evan evan    3581 2005-08-21 12:22 evolver.1

6.grep - look for a word, or combo of words in files

	evan@ELEMLEY-LINUX:~/Desktop/evolver$ grep Quick README
	Quick start:

	Use ^ before to search for beginning of line and $ after to search end of line

7.piping (|) - pipe results of one command to another

	evan@ELEMLEY-LINUX:~/Desktop/evolver$ cat README test | grep Quick
	Quick start: