sahinakkaya.dev/_posts/2022-01-01-stop-cat-pipeing.md

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2022-01-01 16:11:36 +01:00
---
title: "Stop cat-pipe'ing, You Are Doing It Wrong!"
date: 2022-01-01 18:00:00 +0300
2024-08-04 20:13:42 +02:00
classes: wide
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tags: cat grep linux command-line
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---
```bash
cat some_file | grep some_pattern
```
I'm sure that you run a command something like above at least once if you are using terminal. You know how `cat` and `grep` works and you also know what pipe (`|`) does. So you naturally combine all of these to make the job done. I was also doing it this way. What I didn't know is that `grep` already accepts file as an argument. So the above command could be rewritten as:
```bash
grep some_pattern some_file
```
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... which can make you save a few keystrokes and a few nanoseconds of CPU cycles. Phew! Not a big deal if you are not working files that contains GBs of data, right? I agree but you should still use the latter command because it will help you solve some other problems better. Here is a real life scenario: You want to search for some specific pattern in all the files in a directory.
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- If you use the first approach, you may end up running commands like this:
```bash
ls
 config.lua  Git.lua  init.lua  markdown.lua  palette.lua  util.lua
 diff.lua  highlights.lua  LSP.lua  Notify.lua  Treesitter.lua  Whichkey.lua
cat config.lua | grep light
cat diff.lua | grep light
cat Git.lua | grep light
cat highlights.lua | grep light
Pmenu = { fg = C.light_gray, bg = C.popup_back },
CursorLineNr = { fg = C.light_gray, style = "bold" },
Search = { fg = C.light_gray, bg = C.search_blue },
IncSearch = { fg = C.light_gray, bg = C.search_blue },
cat init.lua | grep light
local highlights = require "onedarker.highlights"
highlights,
# You still have a lot to do :/
```
- If you use the second approach, you will immediately realize that you can send all the files with `*` operator and you will finish the job with just one command (2 if you include mandatory `ls` :D):
```bash
ls
 config.lua  Git.lua  init.lua  markdown.lua  palette.lua  util.lua
 diff.lua  highlights.lua  LSP.lua  Notify.lua  Treesitter.lua  Whichkey.lua
grep light *
highlights.lua: Pmenu = { fg = C.light_gray, bg = C.popup_back },
highlights.lua: CursorLineNr = { fg = C.light_gray, style = "bold" },
highlights.lua: Search = { fg = C.light_gray, bg = C.search_blue },
highlights.lua: IncSearch = { fg = C.light_gray, bg = C.search_blue },
init.lua:local highlights = require "onedarker.highlights"
init.lua: highlights,
LSP.lua: NvimTreeNormal = { fg = C.light_gray, bg = C.alt_bg },
LSP.lua: LirFloatNormal = { fg = C.light_gray, bg = C.alt_bg },
markdown.lua: markdownIdDelimiter = { fg = C.light_gray },
markdown.lua: markdownLinkDelimiter = { fg = C.light_gray },
palette.lua: light_gray = "#abb2bf",
palette.lua: light_red = "#be5046",
util.lua:local function highlight(group, properties)
util.lua: "highlight",
util.lua: highlight(group, properties)
```
Isn't this neat? You might say that *"This is cheating! You are using a wild card, of course it will be easier."* Well, yes. Technically I could use the same wild card in the first command like `cat * | grep light` but:
- I figured that out only after using wild card in the second command. So I think it is does not feel natural.
- It is still not giving the same output. Try and see the difference! [*](## "You will not be able to see which file contains which line. 'cat' will just concatenate all the input.")