bash

bash

Bash and bash utils: how to do some stuff on the command line. Scripting, common utils, etc.

GNU Readline

I never learned EMACS, so I never remember this stuff. But it's handy e.g. when you're trying to edit a line in IRC or something.

https://en.wikipedia.org/wiki/GNU_Readline

renaming files

for file in *.png; do mv "$file" "${file/pattern/pattern}"; done

finding files

• Find by file name/type: find . -type f -name *.css

• Find by recently changed: find . -type f -name *.vue -ctime -3

searching

• Search .js, .jsx, .vue files, ignore case: ag --js -i orderservice

suspend and resume jobs

1. C-z to suspend a job, like vim e.g.

2. jobs to see suspended job

3. fg %n to "foreground" a suspended job by its number. (Or just fg to resume the most recent job.)

zero pad

change png to jpg or whatever as needed

#!/bin/bash
num=`echo $1 | sed -n 's/\([0-9]*\).png/\1/p'`
paddednum=`printf "%03d" $num`
echo ${paddednum}.png

Test it with ./zeropad.sh 1.png or whatever. When you're confident it works, you can:

for i in *.jpg; do mv $i `./zeropad.sh $i`; done

loops

for i in {1..5}
do
  echo "Hello `printf "%03d" $i`"
done

diffing and patching

Create a patchfile:

diff -u original new > patchfile

apply the patch:

patch < patchfile

Diff two directories (optionally include -pN where N = depth):

diff -ru original/ new/ > patchfile

Reverse a diff

patch -R < patchfile

converting images

make some weird lo-res images:

convert img.png +dither -remap netscape: convert_img.png

expansion and substituion

http://mywiki.wooledge.org/BashFAQ/073