linux commands all
📊 Linux Command Table with Real-Time Scenarios
1
pwd
Print current working directory
Useful when you log into a remote machine and want to know your location in the file system
2
ls
List contents of a directory
To view files and folders in the current location
3
ls -l
List contents with detailed info
Check file permissions, size, and last modification time
4
ls -lt
Sort files by modification time (newest first)
See the most recently modified files
5
ls -lrt
Sort files by modification time (oldest first)
See the oldest modified files at the top
6
cd ..
Move up one directory
Navigate up in the folder structure
7
cd ../..
Move up two directories
Quickly return to a higher-level directory
8
cd /home/user/path
Change to a specific absolute path
Navigate directly to a known location
9
mkdir <directory_name>
Create a new directory
Create a folder to organize files
10
mkdir dir1 dir2 dir3
Create multiple directories
Efficient for setting up initial folder structure
11
mkdir -p d3/dir1/dir2
Create nested directories
Avoid errors when creating directories deep in hierarchy
12
touch <file_name>
Create a new empty file
Used to quickly create a placeholder file
13
touch f1 f2 f3
Create multiple empty files
Batch file creation for testing or setup
14
touch directory_name/filename
Create file in specific directory
Prepare config or input files in target location
15
vi file_name
Open a file in vi editor
Edit server-side files without GUI
16
cat filename
Display file content
Quick preview of log or config files
17
more filename
View file content page by page
Read long files in chunks without editing
18
less filename
View file with navigation support
Read and search within files efficiently
19
du -sh filename
Show file size in human-readable format
Monitor space used by individual files
20
du -sh <directory>
Show directory size
Identify heavy directories consuming disk space
21
du -sh *
Show size of all items in directory
Overview of space used by each item
22
df -h
Show disk usage in human-readable format
Check available space on mounted partitions
23
head filename
Display first 10 lines of a file
Preview top of logs or config files
24
head -5 filename
Display first 5 lines of file
Focused inspection of small file segments
25
tail filename
Display last 10 lines of file
Check recent log entries
26
tail -3 filename
Show last 3 lines
Quickly view latest changes
27
`
`
`
28
``head -6 filename
tail -1``
Show specific line in file
29
``ls -ltr
wc -l``
Count number of files
30
grep -i "devops" file
Case-insensitive search
Find all mentions of 'DevOps' in a file
✅ Linux Commands Table (Entries 31–60)
31
grep -in "devops" file
Case-insensitive search with line numbers
Quickly locate where “DevOps” appears in a config file
32
grep -ic "devops" file
Count case-insensitive matches
Know how many times “DevOps” appears
33
grep -iw "devops" file
Match whole word (case-insensitive)
Avoid matching substrings like “devopsing”
34
grep -il "devops" *
List files that contain “DevOps”
Search across multiple files for relevant content
35
grep -ilR "devops" *
Recursively list files with “DevOps”
Find where a setting exists in nested config directories
36
grep -ie "pattern1" -ie "pattern2"
Search for multiple patterns
Search for multiple keywords in logs
37
ls -a
Show all files including hidden
View .git, .bashrc, etc.
38
df -h .
Disk space of current directory in human-readable format
Check available space before backups
39
free -g or free -m
Check memory usage in GB or MB
Monitor memory usage on a server
40
uniq file
Remove duplicate lines
Clean a sorted log or config file
✅ Linux Commands Table (Entries 61–90)
61
``sort file
uniq``
Sort and remove duplicates
62
``sort -r file
uniq``
Reverse sort and remove duplicates
63
chmod 777 filename
Give all permissions to everyone
For testing access (not secure in prod)
64
chmod 777 directory
Same as above for a directory
Grant temp access to all users
65
chmod 644 file1
Owner can write, others read
Default permission for config files
66
chmod 755 file1
Owner all, others read/execute
For scripts or binaries
67
chmod -R 777 folder1
Recursive permission change
Fix access issues in nested folders
68
chmod a+w file
Give write permission to all
Allow multi-user write access
69
chmod a+rwx folder
Full access to everyone
Temporary full access for troubleshooting
70
chmod u+rw file
Add read/write to user
Allow owner to edit
71
chmod g+w directory
Group write permission
Shared team folder access
72
chmod o+r file
Others read access
Share logs with read-only access
73
umask 641
Default file permissions mask
Control default permissions for security
74
umask 777
No permissions by default
Testing how apps behave on no access
75
umask 000
Full permissions by default
Used in insecure/dev environments
76
rm filename
Remove file
Delete temporary or unused files
77
rm -rf directory
Force delete directory recursively
Clean up unneeded directory trees
78
rm f1 f2 f3
Delete multiple files
Bulk deletion of test files
79
rm -rf folder1 folder2
Delete multiple directories
Clean multiple old backups
80
rm dir/dir1/file
Delete specific file in path
Remove wrong files placed in nested paths
81
rm -rf /dir1/dir2/dir3
Deep folder deletion
Remove obsolete build or cache directories
82
mv old_name new_name
Rename a file or directory
Rename configs or scripts
83
mv file dir1/file
Move file to directory
Organize files into folders
84
mv dir2/f1 .
Move file to current directory
Pull a file out from nested folder
85
cp file file2
Copy file to new file
Create a backup or duplicate
86
cp file dir1/dir2/file
Copy to nested path
Deploy config to target folder
87
cp -i file file2
Interactive copy (asks before overwrite)
Avoid accidental overwrites
88
cp -i test dir1/test
Interactive copy to directory
Safe file deployment
89
cp -r dir2 dir3
Copy folder recursively
Backup or duplicate folder
90
cp -r dir1 dir2/dir3/dir4
Deep folder copy
Create structured backup copies
✅ Linux Commands Table (Entries 91–120)
91
cp -i dir1/file dir2/dir3/dir4/
Interactive file copy to deep path
Controlled deployment of config or script
92
ls Devops*
List files starting with “Devops”
View all DevOps-related files
93
ls test*
List files starting with “test”
List test files before deletion
94
ls *
List all files in current directory
Check full directory contents
95
grep -i "^Devops" file
Find lines starting with “Devops”
Identify log or config entries
96
grep -i "^t" file
Find lines starting with “t”
Useful in parsing data
97
grep -i "dev$" file
Find lines ending with “dev”
Validate naming conventions
98
chown new_name file
Change file ownership
Assign correct owner to logs/scripts
99
chown new_name:new_grp file
Change owner and group
Fix ownership issues in shared dirs
100
sed
Stream editor for filtering/modifying text
Used in log parsing or automation
101
sed 's/old/new/g' file
Replace all old with new in file
Update variables in config files
102
sed 's/samsung/sony/g' file
Replace brand names
Product migration in data
103
sed -i 's/old/new/g' file
In-place replacement
Auto-update multiple config files
104
sed 's/text/replacement/gi'
Case-insensitive global replace
Change all variants of a keyword
105
sed '2s/text/new/gi'
Replace on specific line
Fix specific line in script or config
106
sed '10,30s/a/b/g'
Replace in line range
Modify a specific block in a file
107
sed '30,$s/a/b/g'
Replace from line 30 to end
Useful in appending or tail-end configs
108
sed -n '98p' file
Print only line 98
Extract specific config or log line
109
sed -n '2p' file
Print only second line
Verify headers in CSV/TSV
110
sed -n '10,20p' file
Print line range
Extract partial config
111
sed '2d' file
Delete second line
Remove unwanted config header
112
sed '100d' file
Delete line 100
Remove old cronjob/script
113
cut -d " " -f1 file
Cut first column by space
Extract usernames or IDs
114
cut -d " " -f3 file
Extract third column
Pull email/port/date etc. from logs
115
cut -d " " -f1,2 file
Extract multiple fields
Combine name + ID, etc.
116
awk -F " " '{print $2}' file
Print second field
Filter by column like CPU usage
117
awk -F " " '{print $3}' file
Print third field
Extract IP, status, values
118
awk -F " " '{print $NF}' file
Print last field
Get final status in logs
119
awk -F " " '{print $(NF-1)}' file
Print second-last field
Pull second-last value from log
120
awk -F " " '{print $1,$3}' file
Print selected fields
Custom field combination for analysis
✅ Linux Commands Table (Entries 121–150)
121
ps -ef
Show all running processes
Monitor system activity
122
``ps -ef
grep -i "service"``
Find specific process
123
``ps -ef
grep -ie "p1" -ie "p2"``
Search for multiple processes
124
kill -9 <pid>
Forcefully kill a process
Stop a hung or runaway process
125
service <name> stop
Stop a service
Stop Apache, MySQL, etc.
126
service <name> start
Start a service
Start server processes
127
service <name> restart
Restart a service
Apply config changes with restart
128
ps -u username
Show processes by user
Monitor specific user activity
129
ps -u ubuntu
Same as above for ubuntu user
Check default user usage
130
adduser username
Add a new user
Create new system accounts
131
find . -iname "test"
Case-insensitive search for file/dir
Locate files regardless of case
132
find . -iname "dir"
Search for directories by name
Locate folders in dev environments
133
find /path -iname "dir2"
Search absolute path
Find folder in entire workspace
134
find . -type f -iname "test"
Search only files by name
Filter only files, not directories
135
find . -type d -iname "test"
Search only directories
Used in organizing/migrating projects
136
find . -type f -mtime -10
Files modified in last 10 days
Check for recent updates
137
find . -type d -mtime -10
Directories modified recently
Detect recent deployments
138
find . -type d -mtime +5
Directories older than 5 days
Archive old logs or backups
139
find . -type f -mtime +20
Files older than 20 days
Identify cleanup candidates
140
find . -type f -mmin -5
Files modified in last 5 mins
Spot real-time log or file updates
141
find . -type d -mmin -15
Recent directory changes
Track deployments
142
find . -type f -mmin -15
Recent file changes
Audit fresh activity in logs
143
find . -type f -perm 777
World-writable files
Find insecure files
144
find . -type d -perm 644
Directories with wrong perms
Detect permission issues
145
find . -perm 755
Standard permission check
Audit executable paths
146
find . -type f -empty
Empty files
Identify unused config/test files
147
find . -type f -not -empty
Non-empty files
Locate real/active files
148
xargs
Build and execute command lines from input
Used with find to delete/search efficiently
149
``find . -type f -mtime +2
xargs rm``
Delete files older than 2 days
150
``find . -type f -mtime +365
xargs rm``
Delete files older than 1 year
✅ Linux Commands (151–174)
151
find . -type f -iname "test" -maxdepth 1
Find matching files in current directory only
Avoid deep search and improve speed
152
find . -type d -iname "test" -maxdepth 2
Find matching directories with limited depth
Used in controlled structure searches
153
find . -iname "test" -maxdepth 1
Find files or dirs by name in current level
Quick validation of naming convention
154
ln -s test1 softlink
Create symbolic (soft) link
Shortcut to config/log/scripts
155
ln -s /home/test/test1 softlink
Softlink to absolute path
Share file across directories
156
ln /home/test/test1 hardlink
Create hard link
Duplicate a file with shared inode
157
uname -a
Show kernel and OS info
Check system version and architecture
158
cat /etc/os-release
Show OS release info
Confirm Linux distribution (Ubuntu, CentOS, etc.)
159
hostname
Display system hostname
Check system identity
160
``who
wc -l``
Count logged-in users
161
whoami
Show current user
Identify running user context
162
nohup ./script.sh &
Run script in background with no hangup
Keep processes running after logout
163
top
Display running processes dynamically
Real-time monitoring of CPU/memory usage
164
ssh username@server
Connect to remote server via SSH
Administer or deploy on remote Linux server
165
ssh -i demo.pem user@server
Connect to EC2 using key pair
Login securely to AWS instance
166
ssh -i demo.pem ubuntu@<ip>
SSH login with Ubuntu user
Standard AWS EC2 login for Ubuntu
167
scp file user@server:/tmp
Copy file to remote server
Transfer logs/configs
168
scp file user@server:/home/ubuntu
Copy file to user's home directory
Deploy scripts
169
scp -r dir user@server:/path
Recursively copy directory
Full folder backup or deployment
170
rsync file user@server:/path
Efficient file synchronization
Backup with delta transfer
171
ping google.com
Check connectivity
Test internet or DNS resolution
172
ping IP_ADDRESS
Ping by IP
Check server or service status
173
telnet IP or telnet hostname
Test TCP connection to a host
Validate port access/firewall
174
``netstat -na
grep 8080``
Check if port 8080 is listening