This page will be updated with new concepts for each lecture.
Command/Program | Description | example/syntax |
---|---|---|
9/4/18 - Scripting, executable permissions/conventions. | ||
chmod | Change the mode of a file or directory | chmod MODE FILE |
chmod OCTAL-MODE FILE |
||
echo | “echo” values to the screen | echo “string $varname” |
nano | Edit a file | nano FILE |
rev | reverse input stream | echo “abcd” | rev |
touch | Update file modification time. Create file if necessary | touch FILE |
tr | Translate or delete characters | tr [SET1] [SET2] |
which | Location of an executable in your PATH | which ls |
9/6/18 | ||
9/11/18 |
Variable name | Description | example/syntax |
---|---|---|
9/4/18 - Scripting, executable permissions/conventions. | ||
HOME | Your home directory. Same as tilde (~ ) | /home/yourname |
PATH | Search path for executables. | /bin:/usr/bin:$HOME/bin |
PS1 | Your prompt string. | [\h \w] |
PWD | Your current directory, same as pwd | ~/dev |
USER | Your login/account, same as whoami | eid@colostate.edu |
9/6/18 | ||
9/11/18 |
Keyword(s)/Operators | Description | Example |
---|---|---|
9/4/18 - Scripting, executable permissions/conventions. | ||
[ ] | conditional | [ -z “” ] |
if,then,else,fi | flow control | if [ -z “” ]; then echo 'empty!'; else echo 'NOT empty!'; fi |
test | flow control | test -z “” |
&& || | boolean operators for flow control | [ -z “” ] && echo 'empty!' || echo 'NOT empty! ' |
9/6/18 | ||
let | arithmetic assignment | a=1; let a=a+1; |
$((expr)) | arithmetic expressions | echo $((a+1)) |
while | loop | a=0; while [ $a -lt 10 ]; do echo $a; let a=a+1; done |
for var in list | loop | for num in 1 2 3; do echo $num; done |
9/11/18 |