ls -l | grep '^-' | awk '{print $5,$9}' |sort -n|awk '{print $2}'
2. Write a command to search for the file 'map' in the current directory?
find -name map -type f
3. How to display the first 10 characters from each line of a file?
cut -c -10 filename
4. Write a command to remove the first number on all lines that start with "@"?
sed '\,^@, s/[0-9][0-9]*//' < filename
5. How to print the file names in a directory that has the word "term"?
grep -l term *
The '-l' option make the grep command to print only the filename without printing the content of the file. As soon as the grep command finds the pattern in a file, it prints the pattern and stops searching other lines in the file.
6. How to run awk command specified in a file?
awk -f filename
7. How do you display the calendar for the month march in the year 1985?
The cal command can be used to display the current month calendar. You can pass the month and year as arguments to display the required year, month combination calendar.
cal 03 1985
This will display the calendar for the March month and year 1985.
8. Write a command to find the total number of lines in a file?
wc -l filename
Other ways to pring the total number of lines are
awk 'BEGIN {sum=0} {sum=sum+1} END {print sum}' filename
awk 'END{print NR}' filename
9. How to duplicate empty lines in a file?
sed '/^$/ p' < filename
10. Explain iostat, vmstat and netstat?
- Iostat: reports on terminal, disk and tape I/O activity.
- Vmstat: reports on virtual memory statistics for processes, disk, tape and CPU activity.
- Netstat: reports on the contents of network data structures.
11. Write a command to print the lines that has the the pattern "july" in all the files in a particular directory?
grep july *
This will print all the lines in all files that contain the word “july” along with the file name. If any of the files contain words like "JULY" or "July", the above command would not print those lines.
12. Write a command to print the lines that has the word "july" in all the files in a directory and also suppress the filename in the output.
grep -h july *
13. Write a command to print the lines that has the word "july" while ignoring the case.
grep -i july *
The option i make the grep command to treat the pattern as case insensitive.
14. When you use a single file as input to the grep command to search for a pattern, it won't print the filename in the output. Now write a grep command to print the filename in the output without using the '-H' option.
grep pattern filename /dev/null
The /dev/null or null device is special file that discards the data written to it. So, the /dev/null is always an empty file.
Another way to print the filename is using the '-H' option. The grep command for this is
grep -H pattern filename
15. Write a command to print the file names in a directory that does not contain the word "july"?
grep -L july *
The '-L' option makes the grep command to print the filenames that do not contain the specified pattern.
16. Write a command to print the line numbers along with the line that has the word "july"?
grep -n july filename
The '-n' option is used to print the line numbers in a file. The line numbers start from 1
17. Write a command to print the lines that starts with the word "start"?
grep '^start' filename
The '^' symbol specifies the grep command to search for the pattern at the start of the line.
18. In the text file, some lines are delimited by colon and some are delimited by space. Write a command to print the third field of each line.
awk '{ if( $0 ~ /:/ ) { FS=":"; } else { FS =" "; } print $3 }' filename
19. Write a command to print the line number before each line?
awk '{print NR, $0}' filename
20. Write a command to print the second and third line of a file without using NR.
awk 'BEGIN {RS="";FS="\n"} {print $2,$3}' filename
21. How to create an alias for the complex command and remove the alias?
The alias utility is used to create the alias for a command. The below command creates alias for ps -aef command.
alias pg='ps -aef'
If you use pg, it will work the same way as ps -aef.
To remove the alias simply use the unalias command as
unalias pg
22. Write a command to display todays date in the format of 'yyyy-mm-dd'?
The date command can be used to display todays date with time
date '+%Y-%m-%d'
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