edit bash_tricks

system/bash_tricks.md

@@ -1,46 +1,18 @@
 ---
-title: "bash_tricks"
+title: "Terminal Tips"
 tags: [ "Documentation", "System" ]
 ---
-# Track Live Changes
+## Track Live Changes
 
 See changes in a file as it changes:
 
-> tail -f *somefile*
+`tail -f *somefile*`
 
 See changes in a directory, as it changes:
 
-> watch -d ls *directory*
+`watch -d ls *directory*`
 
-# Automatic mp3 Tagging
+## Automatic Renaming
-
-> !/usr/bin/env bash
-> IFS=$'\n'
-> for f in $(find . -type f); do
-    > id3tool $f -t $(basename $f | cut -d- -f3 | sed 's/\.[^\,]*$//')
-> done
-
-One can also use
-
-> sed s/\,[^\.]\*$//
-
-... in order to avoid multiple full stops messing up syntax.
-
-We can use `\.` as a literal full stop.
-
-`[^ ]` means anything other than the containing character, so `[^\.]` would mean `anything other than a full stop'.
-
-`*` in sed means this character is repeated any number of times, including 0, so files with no `.` character would still be processed fine.
-
-`$` means `end of the line'.
-
-Apparently sed uses `regex, not globing'.
-
-Regular expressions (``regex'') looks for patterns and is used with find and grep.  It interprets `*' as a wildcard, `?' as a single-character wildcard, and [12,1,2] as characters matching one of a set (in this case, `12 or 1 or 2 but not 21'].
-
-If the shell is set to find file ``a*b.txt'' then it will pass this first to regex, and hit items like `aab.txt' and `abb.txt'.  If it finds nothing, it'll then use globbing, and interpret `a*b.txt' literally.
-
-# Automatic Renaming
 
 There are a bunch of files:
 
@@ -53,50 +25,49 @@ There are a bunch of files:
 
 Goal: swap the word "Column" for "Alice" in all files.
 
-> IFS=$'\n'
+```
-
+IFS=$'\n'
-> for f in $(find . -name "Col*"); do
+for f in $(find . -name "Col*"); do
-
+mv "$f" $(echo "$f" | sed s/Column/Alice/)
-> mv "$f" $(echo "$f" | sed s/Column/Malin/)
+done
-
+```
-> done
 
 IFS is the field separator.  This is required to denote the different files as marked by a new line, and not the spaces.
 
-# Arguments and Input
+## Arguments and Input
 
 The `rm' program takes arguments, but not `stdin' from a keyboard, and therefore programs cannot pipe results into rm.
 
 That said, we can sometimes pipe into rm with `xargs rm' to turn the stdin into an argument.  For example, if we have a list of files called `list.txt' then we could use cat as so:
 
-> cat list.txt | xargs rm
+```bash
+cat list.txt | xargs rm
+```
 
 ... *However*, this wouldn't work if spaces were included, as rm would take everything literally.
 
-# Numbers
+## Numbers
 
 Add number to variables with:
 
-* > let "var=var+1"
+* `let "var=var+1"`
-* > let "var+=1"
+* `let "var+=1"`
-* > let "var++"
+* `let "var++"`
-* > ((++var))
+* `((++var))`
-* > ((var=var+1))
+* `((var=var+1))`
-* > ((var+=1))
+* `((var+=1))`
-* > var=$(expr $var + 1)
+* `var=$(expr $var + 1)`
 
-((n--)) works identically.
+`((n--))` works identically.
 
-# Finding Duplicate Files
+## Finding Duplicate Files
 
-> find . -type f -exec md5sum '{}' ';' | sort | uniq --all-repeated=separate -w 15 > all-files.txt
+```bash
+find . -type f -exec md5sum '{}' ';' | sort | uniq --all-repeated=separate -w 15 > all-files.txt
+```
 
-... add blank line to top of first file.
+## Output random characters
 
-> awk '/^$/{getline;print;}' all-files.txt > uniq.txt
+```bash
-
+cat /dev/urandom | tr -cd [:alnum:] | dd bs=1 count=200 status=none && echo
-> diff all-files.txt uniq.txt | grep '/' | cut -d '.' -f 2,3,4,5 | sed 's#/##' | sed 's/ /\\ /g' | xargs rm
+```
-
-Output random characters.
-
-> cat /dev/urandom | tr -cd [:alnum:] | dd bs=1 count=200 status=none && echo