hans/pure-bash-bible
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Added build files to turn the bible into a book

Browse Source
This commit is contained in:
Dylan Araps
2018-06-20 12:40:31 +10:00
parent e0aadbde13
commit fe6e2cd195
21 changed files with 1310 additions and 1440 deletions
Download Patch File Download Diff File Expand all files Collapse all files

82
manuscript/chapter8.txt
View File

@@ -1,68 +1,42 @@
# Parameter Expansion
# Brace Expansion
## Indirection
## Ranges
| Parameter | What does it do? |
| --------- | ---------------- |
| `${!VAR}` | Access a variable based on the value of `VAR`. See: [link](#assign-and-access-a-variable-using-a-variable)
| `${!VAR*}` | Expand to `IFS` separated list of variable names starting with `VAR`. |
| `${!VAR@}` | Expand to `IFS` separated list of variable names starting with `VAR`. |
```shell
# Syntax: {<START>..<END>}
# Print numbers 1-100.
echo {1..100}
## Replacement
# Print range of floats.
echo 1.{1..9}
| Parameter | What does it do? |
| --------- | ---------------- |
| `${VAR#PATTERN}` | Remove shortest match of pattern from start of string. |
| `${VAR##PATTERN}` | Remove longest match of pattern from start of string. |
| `${VAR%PATTERN}` | Remove shortest match of pattern from end of string. |
| `${VAR%%PATTERN}` | Remove longest match of pattern from end of string. |
| `${VAR/PATTERN/REPLACE}` | Replace first match with string.
| `${VAR//PATTERN/REPLACE}` | Replace all matches with string.
| `${VAR/PATTERN}` | Remove first match.
| `${VAR//PATTERN}` | Remove all matches.
# Print chars a-z.
echo {a..z}
echo {A..Z}
## Length
# Nesting.
echo {A..Z}{0..9}
| Parameter | What does it do? |
| --------- | ---------------- |
| `${#VAR}` | Length of var in characters.
| `${#ARR[@]}` | Length of array in elements.
# Print zero-padded numbers.
# CAVEAT: bash 4+
echo {01..100}
## Expansion
# Change increment amount.
# Syntax: {<START>..<END>..<INCREMENT>}
# CAVEAT: bash 4+
echo {1..10..2} # Increment by 2.
```
| Parameter | What does it do? |
| --------- | ---------------- |
| `${VAR:OFFSET}` | Remove first `N` chars from variable.
| `${VAR:OFFSET:LENGTH}` | Get substring from `N` character to `N` character. <br> (`${VAR:10:10}`: Get sub-string from char `10` to char `20`)
| `${VAR:: OFFSET}` | Get first `N` chars from variable.
| `${VAR:: -OFFSET}` | Remove last `N` chars from variable.
| `${VAR: -OFFSET}` | Get last `N` chars from variable.
| `${VAR:OFFSET:-OFFSET}` | Cut first `N` chars and last `N` chars. | `bash 4.2+` |
## String Lists
## Case Modification
| Parameter | What does it do? | CAVEAT |
| --------- | ---------------- | ------ |
| `${VAR^}` | Uppercase first character. | `bash 4+` |
| `${VAR^^}` | Uppercase all characters. | `bash 4+` |
| `${VAR,}` | Lowercase first character. | `bash 4+` |
| `${VAR,,}` | Lowercase all characters. | `bash 4+` |
## Default Value
| Parameter | What does it do? |
| --------- | ---------------- |
| `${VAR:-STRING}` | If `VAR` is empty or unset, use `STRING` as it's value.
| `${VAR-STRING}` | If `VAR` is unset, use `STRING` as it's value.
| `${VAR:=STRING}` | If `VAR` is empty or unset, set the value of `VAR` to `STRING`.
| `${VAR=STRING}` | If `VAR` is unset, set the value of `VAR` to `STRING`.
| `${VAR:+STRING}` | If `VAR` isn't empty, use `STRING` as it's value.
| `${VAR+STRING}` | If `VAR` is set, use `STRING` as it's value.
| `${VAR:?STRING}` | Display an error if empty or unset.
| `${VAR?STRING}` | Display an error if unset.
```shell
echo {apples,oranges,pears,grapes}
# Example Usage:
# Remove dirs Movies, Music and ISOS from ~/Downloads/.
rm -rf ~/Downloads/{Movies,Music,ISOS}
```
<!-- CHAPTER END -->