Nash provides powerful file manipulation tools that let you work efficiently with files and directories.
Creating and Reading Files
Creating Files
Empty files
Files with content
Multi-line files
user@nash:/home/user$ touch file1.txt file2.txt file3.txt
user@nash:/home/user$ ls
file1.txt file2.txt file3.txt
user@nash:/home/user$ echo "Hello World" > greeting.txt
user@nash:/home/user$ cat greeting.txt
Hello World
user@nash:/home/user$ echo "Line 1" > document.txt
user@nash:/home/user$ echo "Line 2" >> document.txt
user@nash:/home/user$ echo "Line 3" >> document.txt
user@nash:/home/user$ cat document.txt
Line 1
Line 2
Line 3
Reading Files
user@nash:/home/user$ cat document.txt
Line 1
Line 2
Line 3
Copying and Moving Files
Copy Files
user@nash:/home/user$ echo "original" > source.txt
user@nash:/home/user$ cp source.txt backup.txt
user@nash:/home/user$ cat backup.txt
original
user@nash:/home/user$ ls
backup.txt source.txt
user@nash:/home/user$ mkdir archives
user@nash:/home/user$ cp source.txt backup.txt archives/
user@nash:/home/user$ ls archives/
backup.txt source.txt
Move/Rename Files
user@nash:/home/user$ mv source.txt renamed.txt
user@nash:/home/user$ ls
archives/ backup.txt renamed.txt
user@nash:/home/user$ mkdir old
user@nash:/home/user$ mv backup.txt old/
user@nash:/home/user$ ls old/
backup.txt
Finding Files
The find command searches for files based on various criteria.
Basic Find Operations
Find all files
user@nash:/home/user$ find .
.
./Desktop
./Documents
./Downloads
./welcome.txt
./renamed.txt
./old
./old/backup.txt
./archives
./archives/backup.txt
./archives/source.txt
Find only files
user@nash:/home/user$ find . -type f
./welcome.txt
./renamed.txt
./old/backup.txt
./archives/backup.txt
./archives/source.txt
Find only directories
user@nash:/home/user$ find . -type d
.
./Desktop
./Documents
./Downloads
./old
./archives
Find by Name Pattern
user@nash:/home/user$ touch app.js utils.js config.json package.json
user@nash:/home/user$ find . -name "*.js"
./app.js
./utils.js
user@nash:/home/user$ find . -name "*.json"
./config.json
./package.json
user@nash:/home/user$ find . -name "*backup*"
./old/backup.txt
./archives/backup.txt
Find with Depth Limit
user@nash:/home/user$ mkdir -p deep/nested/structure
user@nash:/home/user$ touch deep/file1.txt
user@nash:/home/user$ touch deep/nested/file2.txt
user@nash:/home/user$ touch deep/nested/structure/file3.txt
user@nash:/home/user$ find deep -type f
deep/file1.txt
deep/nested/file2.txt
deep/nested/structure/file3.txt
user@nash:/home/user$ find deep -maxdepth 1 -type f
deep/file1.txt
user@nash:/home/user$ find deep -maxdepth 2 -type f
deep/file1.txt
deep/nested/file2.txt
Text Processing with Grep
The grep command searches for patterns in text.
Basic Grep
user@nash:/home/user$ cat > employees.txt
Alice Developer
Bob Designer
Charlie Developer
Diana Manager
Eve Developer
user@nash:/home/user$ grep "Developer" employees.txt
Alice Developer
Charlie Developer
Eve Developer
user@nash:/home/user$ grep "Manager" employees.txt
Diana Manager
Grep Options
Case-insensitive
Line numbers
Invert match
user@nash:/home/user$ grep -i "developer" employees.txt
Alice Developer
Charlie Developer
Eve Developer
user@nash:/home/user$ grep -n "Developer" employees.txt
1:Alice Developer
3:Charlie Developer
5:Eve Developer
user@nash:/home/user$ grep -v "Developer" employees.txt
Bob Designer
Diana Manager
Grep with Pipes
user@nash:/home/user$ cat employees.txt | grep "Developer" | wc -l
3
user@nash:/home/user$ ls | grep ".txt$"
employees.txt
file1.txt
welcome.txt
user@nash:/home/user$ env | grep "HOME"
HOME=/home/user
Stream Editing with Sed
The sed command performs text transformations.
Substitution
user@nash:/home/user$ echo "Hello World" | sed 's/World/Nash/'
Hello Nash
user@nash:/home/user$ echo "foo foo foo" | sed 's/foo/bar/'
bar foo foo
user@nash:/home/user$ echo "foo foo foo" | sed 's/foo/bar/g'
bar bar bar
Sed on Files
user@nash:/home/user$ cat > config.txt
server=localhost
port=8080
server=localhost
user@nash:/home/user$ sed 's/localhost/0.0.0.0/' config.txt
server=0.0.0.0
port=8080
server=localhost
user@nash:/home/user$ sed 's/localhost/0.0.0.0/g' config.txt
server=0.0.0.0
port=8080
server=0.0.0.0
Line Deletion
user@nash:/home/user$ cat > numbers.txt
line 1
line 2
line 3
line 4
user@nash:/home/user$ sed '2d' numbers.txt
line 1
line 3
line 4
user@nash:/home/user$ sed 'd' numbers.txt
cut command extracts specific fields from text.
Cut by Delimiter
user@nash:/home/user$ cat > data.csv
Alice,30,Engineer
Bob,25,Designer
Charlie,35,Manager
user@nash:/home/user$ cut -d',' -f1 data.csv
Alice
Bob
Charlie
user@nash:/home/user$ cut -d',' -f2 data.csv
30
25
35
user@nash:/home/user$ cut -d',' -f1,3 data.csv
Alice,Engineer
Bob,Designer
Charlie,Manager
Cut by Character Position
user@nash:/home/user$ echo "ABCDEFGH" | cut -c1-3
ABC
user@nash:/home/user$ echo "ABCDEFGH" | cut -c5-8
EFGH
user@nash:/home/user$ echo "ABCDEFGH" | cut -c1,3,5
ACE
JSON Processing with jq
The jq command is a powerful JSON processor.
Basic jq Operations
user@nash:/home/user$ cat > user.json
{
"name": "Alice",
"age": 30,
"email": "[email protected]",
"active": true
}
user@nash:/home/user$ cat user.json | jq '.'
{
"name": "Alice",
"age": 30,
"email": "[email protected]",
"active": true
}
user@nash:/home/user$ cat user.json | jq '.name'
"Alice"
user@nash:/home/user$ cat user.json | jq '.age'
30
user@nash:/home/user$ cat user.json | jq -r '.email'
[email protected]
Working with Arrays
user@nash:/home/user$ cat > users.json
[
{"id": 1, "name": "Alice"},
{"id": 2, "name": "Bob"},
{"id": 3, "name": "Charlie"}
]
user@nash:/home/user$ cat users.json | jq '.[0]'
{
"id": 1,
"name": "Alice"
}
user@nash:/home/user$ cat users.json | jq '.[1].name'
"Bob"
user@nash:/home/user$ cat users.json | jq '.[]'
{
"id": 1,
"name": "Alice"
}
{
"id": 2,
"name": "Bob"
}
{
"id": 3,
"name": "Charlie"
}
jq Filters
user@nash:/home/user$ echo '{"a":1,"b":2,"c":3}' | jq 'keys'
[
"a",
"b",
"c"
]
Directory Tree View
The tree command shows directory structure:
user@nash:/home/user$ mkdir -p project/{src,tests,docs}
user@nash:/home/user$ touch project/README.md
user@nash:/home/user$ touch project/src/main.js project/src/utils.js
user@nash:/home/user$ touch project/tests/test.js
user@nash:/home/user$ touch project/docs/guide.md
user@nash:/home/user$ tree project
project
├── README.md
├── docs/
│ └── guide.md
├── src/
│ ├── main.js
│ └── utils.js
└── tests/
└── test.js
3 directories, 5 files
user@nash:/home/user$ tree -L 1 project
project
├── README.md
├── docs/
├── src/
└── tests/
3 directories, 1 file
Complete Workflow Example
user@nash:/home/user$ mkdir data_analysis && cd data_analysis
user@nash:/home/user/data_analysis$ cat > sales.csv
date,product,quantity,price
2024-01-01,laptop,2,1200
2024-01-02,mouse,5,25
2024-01-02,keyboard,3,80
2024-01-03,laptop,1,1200
2024-01-03,mouse,10,25
user@nash:/home/user/data_analysis$ cat sales.csv | grep -v "^date" | wc -l
5
user@nash:/home/user/data_analysis$ cat sales.csv | grep "laptop"
date,product,quantity,price
2024-01-01,laptop,2,1200
2024-01-03,laptop,1,1200
user@nash:/home/user/data_analysis$ cat sales.csv | grep -v "^date" | cut -d',' -f2 | sort | uniq
keyboard
laptop
mouse
user@nash:/home/user/data_analysis$ cat sales.csv | grep -v "^date" | cut -d',' -f2 | sort | uniq -c
1 keyboard
2 laptop
2 mouse
user@nash:/home/user/data_analysis$ cat sales.csv | grep "laptop" | cut -d',' -f3 > laptop_quantities.txt
user@nash:/home/user/data_analysis$ cat laptop_quantities.txt
quantity
2
1
user@nash:/home/user/data_analysis$ find . -name "*.csv" > csv_files.txt
user@nash:/home/user/data_analysis$ find . -name "*.txt" >> csv_files.txt
user@nash:/home/user/data_analysis$ cat csv_files.txt
./sales.csv
./laptop_quantities.txt
./csv_files.txt
user@nash:/home/user/data_analysis$ tree .
.
├── csv_files.txt
├── laptop_quantities.txt
└── sales.csv
0 directories, 3 files
Command Reference
| Command | Description | Common Options |
|---|
cp | Copy files | source destination |
mv | Move/rename files | source destination |
find | Search for files | -name, -type, -maxdepth |
grep | Search text patterns | -i, -n, -v |
sed | Stream editor | 's/old/new/g', 'Nd' |
cut | Extract fields | -d (delimiter), -f (fields), -c (chars) |
jq | Process JSON | .key, keys, values, length |
tree | Directory tree | -L (depth), -a (hidden) |
head | First lines | -n N |
tail | Last lines | -n N |
Combine these tools with pipes to build powerful data processing pipelines. For example: find | grep | cut | sort | uniq
