Syntax:
grep [OPTIONS] PATTERN [FILE...]
Options:
Option | Description |
---|---|
-i |
Ignore case |
-v |
Invert match |
-r |
Recursive search |
-n |
Show line numbers |
-l |
List matching file names only |
-c |
Count matching lines |
Examples:
grep "error" logfile.txt
grep -i "hello" file.txt
grep -rn "TODO" ./src
grep -v "DEBUG" app.log
Syntax:
awk 'pattern {action}' [FILE...]
Options (within scripts):
Option | Description |
---|---|
$1 , $2 , … |
Columns/fields |
NF |
Number of fields in a line |
NR |
Current record number |
BEGIN |
Run before processing |
END |
Run after all lines |
Examples:
awk '{print $1}' file.txt # Print first column
awk '/error/ {print $0}' log.txt # Print lines containing "error"
awk 'BEGIN{print "Start"}' # Just print "Start"
awk '{sum += $2} END {print sum}' data.txt
Syntax:
sed [OPTIONS] 'command' [FILE...]
Common Commands:
Command | Description |
---|---|
s/pattern/replace/ |
Replace text |
d |
Delete lines |
p |
Print lines |
-n |
Suppress default output |
Examples:
sed 's/apple/orange/' file.txt
sed 's/foo/bar/g' file.txt
sed -n '/hello/p' file.txt # Print only lines containing "hello"
sed '2d' file.txt # Delete 2nd line
Syntax:
cut [OPTIONS] [FILE...]
Options:
Option | Description |
---|---|
-f |
Specify field number |
-d |
Set delimiter (default: tab) |
-c |
Cut by character position |
Examples:
cut -f1 file.txt # First tab-separated field
cut -d',' -f2 file.csv # Second column using comma
cut -c1-5 filename.txt # First 5 characters of each line
Syntax:
sort [OPTIONS] [FILE...]
Options:
Option | Description |
---|---|
-r |
Reverse sort |
-n |
Sort numerically |
-k |
Sort by specific field |
-u |
Remove duplicates |
Examples:
sort file.txt
sort -r file.txt
sort -n numbers.txt
sort -k2 file.csv
sort -u names.txt
Syntax:
tail [OPTIONS] [FILE...]
Options:
Option | Description |
---|---|
-n |
Number of lines to show |
-f |
Follow file (real-time updates) |
Examples:
tail file.txt
tail -n 20 error.log
tail -f /var/log/syslog
Syntax:
head [OPTIONS] [FILE...]
Options:
Option | Description |
---|---|
-n |
Number of lines to show |
Examples:
head file.txt
head -n 15 logfile.log