Humayun Ahmed Ashik

Frequently Used Unix Commands for Software Tester

Unix commands can be very handy during any query result fetching from server log, here are some useful Unix commands for testers.

Humayun Ahmed Ashik's photo
Humayun Ahmed Ashik
·

17 min read

Frequently Used Unix Commands for Software Tester

Photo by Gabriel Heinzer on Unsplash

Table of contents

As a software tester, during backend testing you need the skill set to monitor server logs, finding culprits by analyzing logs, know the processes, network etc. Some unix commands can be very helpful in this regards. So let's get started to explore some useful commands.

date

date command is to view the system time and with different query parameter view the date time like which day was on 1995-04-28, date time of 2 hours ago etc.

root@K-ASHIK-L4:~/linux-command-practice/cat# date
Sun Jun 12 15:53:18 +06 2022
root@K-ASHIK-L4:~/linux-command-practice/cat# date -d "1995-04-28"
Fri Apr 28 00:00:00 +06 1995
root@K-ASHIK-L4:~/linux-command-practice/cat# date --date='2 years ago'
Fri Jun 12 15:54:48 +06 2020
root@K-ASHIK-L4:~/linux-command-practice/cat# date --date='1 month ago'
Thu May 12 15:56:06 +06 2022

uptime

uptime command lets you know the current system load and it's up time.

root@K-ASHIK-L4:~/linux-command-practice/cat# uptime
 15:57:39 up  5:02,  0 users,  load average: 0.00, 0.00, 0.00

cal

  • View calendar of any year

cal.png

  • View calendar of any month of a year: cal MM YYYY

cal2.png

su

su (Switch User) command is used to switch between users:

root@K-ASHIK-L4:~# su - humayun-ashik
To run a command as administrator (user "root"), use "sudo <command>".
See "man sudo_root" for details.
humayun-ashik@K-ASHIK-L4:~$ su - root
Password:
root@K-ASHIK-L4:~#

ps

ps command is used for viewing information related with the processes on a system which stands as abbreviation for “Process Status”.

  • View the processes for the current shell:
root@K-ASHIK-L4:~# ps
  PID TTY          TIME CMD
   79 pts/0    00:00:00 su
   80 pts/0    00:00:03 bash
 1358 pts/0    00:00:00 su
 1374 pts/0    00:00:00 su
 1375 pts/0    00:00:00 bash
 1406 pts/0    00:00:00 ps
  • View all the running processes
root@K-ASHIK-L4:~# ps -e
  PID TTY          TIME CMD
    1 ?        00:00:00 init
    7 ?        00:00:00 init
    8 ?        00:00:02 init
    9 pts/0    00:00:00 bash
   79 pts/0    00:00:00 su
   80 pts/0    00:00:03 bash
 1358 pts/0    00:00:00 su
 1359 pts/0    00:00:00 bash
 1374 pts/0    00:00:00 su
 1375 pts/0    00:00:00 bash
 1407 pts/0    00:00:00 ps
  • View all processes running by you:
root@K-ASHIK-L4:~# ps -x
  PID TTY      STAT   TIME COMMAND
    1 ?        Sl     0:00 /init
    7 ?        Ss     0:00 /init
    8 ?        R      0:02 /init
   79 pts/0    S      0:00 su - root
   80 pts/0    S      0:03 -bash
 1358 pts/0    S      0:00 su - humayun-ashik
 1374 pts/0    S      0:00 su - root
 1375 pts/0    S      0:00 -bash
 1409 pts/0    R+     0:00 ps -x
  • View full format listing using -f option:
root@K-ASHIK-L4:~# ps -ef
UID        PID  PPID  C STIME TTY          TIME CMD
root         1     0  0 10:55 ?        00:00:00 /init
root         7     1  0 10:55 ?        00:00:00 /init
root         8     7  0 10:55 ?        00:00:02 /init
humayun+     9     8  0 10:55 pts/0    00:00:00 -bash
root        79     9  0 10:58 pts/0    00:00:00 su - root
root        80    79  0 10:58 pts/0    00:00:03 -bash
root      1358    80  0 17:06 pts/0    00:00:00 su - humayun-ashik
humayun+  1359  1358  0 17:06 pts/0    00:00:00 -bash
root      1374  1359  0 17:07 pts/0    00:00:00 su - root
root      1375  1374  0 17:07 pts/0    00:00:00 -bash
root      1410  1375  0 17:23 pts/0    00:00:00 ps -ef

kill

kill command is used to manually terminate a process. kill command sends a signal to a process which terminates the process

  • View all the signals:
root@K-ASHIK-L4:~# kill -l
 1) SIGHUP       2) SIGINT       3) SIGQUIT      4) SIGILL       5) SIGTRAP
 6) SIGABRT      7) SIGBUS       8) SIGFPE       9) SIGKILL     10) SIGUSR1
11) SIGSEGV     12) SIGUSR2     13) SIGPIPE     14) SIGALRM     15) SIGTERM
16) SIGSTKFLT   17) SIGCHLD     18) SIGCONT     19) SIGSTOP     20) SIGTSTP
21) SIGTTIN     22) SIGTTOU     23) SIGURG      24) SIGXCPU     25) SIGXFSZ
26) SIGVTALRM   27) SIGPROF     28) SIGWINCH    29) SIGIO       30) SIGPWR
31) SIGSYS      34) SIGRTMIN    35) SIGRTMIN+1  36) SIGRTMIN+2  37) SIGRTMIN+3
38) SIGRTMIN+4  39) SIGRTMIN+5  40) SIGRTMIN+6  41) SIGRTMIN+7  42) SIGRTMIN+8
43) SIGRTMIN+9  44) SIGRTMIN+10 45) SIGRTMIN+11 46) SIGRTMIN+12 47) SIGRTMIN+13
48) SIGRTMIN+14 49) SIGRTMIN+15 50) SIGRTMAX-14 51) SIGRTMAX-13 52) SIGRTMAX-12
53) SIGRTMAX-11 54) SIGRTMAX-10 55) SIGRTMAX-9  56) SIGRTMAX-8  57) SIGRTMAX-7
58) SIGRTMAX-6  59) SIGRTMAX-5  60) SIGRTMAX-4  61) SIGRTMAX-3  62) SIGRTMAX-2
63) SIGRTMAX-1  64) SIGRTMAX
  • kill any process using pid:
root@K-ASHIK-L4:~# ps
  PID TTY          TIME CMD
   79 pts/0    00:00:00 su
   80 pts/0    00:00:03 bash
 1358 pts/0    00:00:00 su
 1374 pts/0    00:00:00 su
 1375 pts/0    00:00:00 bash
 1413 pts/0    00:00:00 ps
root@K-ASHIK-L4:~#
root@K-ASHIK-L4:~# kill 1413
  • For forceful kill:
root@K-ASHIK-L4:~# ps -ef
UID        PID  PPID  C STIME TTY          TIME CMD
root         1     0  0 10:55 ?        00:00:00 /init
root         7     1  0 10:55 ?        00:00:00 /init
root         8     7  0 10:55 ?        00:00:02 /init
humayun+     9     8  0 10:55 pts/0    00:00:00 -bash
root        79     9  0 10:58 pts/0    00:00:00 su - root
root        80    79  0 10:58 pts/0    00:00:03 -bash
root      1358    80  0 17:06 pts/0    00:00:00 su - humayun-ashik
humayun+  1359  1358  0 17:06 pts/0    00:00:00 -bash
root      1374  1359  0 17:07 pts/0    00:00:00 su - root
root      1375  1374  0 17:07 pts/0    00:00:00 -bash
root      1415  1375  0 17:35 pts/0    00:00:00 ps -ef
root@K-ASHIK-L4:~#
root@K-ASHIK-L4:~# kill -9 1374
root@K-ASHIK-L4:~# Killed

ping

-ping command is used to know the connection status from your machine to any destination server

root@K-ASHIK-L4:~# ping google.com
PING google.com (74.125.24.102) 56(84) bytes of data.
From 192.168.43.1 (192.168.43.1) icmp_seq=16 Destination Net Unreachable
^C
--- google.com ping statistics ---
25 packets transmitted, 0 received, +1 errors, 100% packet loss, time 25034ms
pipe 2

free

free command provides information about the total amount of the physical and swap memory, as well as the free and used memory and free memories.

root@K-ASHIK-L4:~/linux-command-practice# free
              total        used        free      shared  buff/cache   available
Mem:        5022200       87728     4758416          72      176056     4726356
Swap:       2097152           0     2097152
root@K-ASHIK-L4:~/linux-command-practice#
root@K-ASHIK-L4:~/linux-command-practice# free -h
              total        used        free      shared  buff/cache   available
Mem:          4.8Gi        85Mi       4.5Gi       0.0Ki       171Mi       4.5Gi
Swap:         2.0Gi          0B       2.0Gi

du

du (Disk Usage) is a standard Unix/Linux command, used to check the information of disk usage of files and directories. 

root@K-ASHIK-L4:~/linux-command-practice# du -h grep/
8.0K    grep/grepfolder
16K     grep/

df

df stands for "disk filesystem" and is used to display the disk space used in the file system.

root@K-ASHIK-L4:~/linux-command-practice# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sdb        251G  1.8G  237G   1% /
none            2.4G  4.0K  2.4G   1% /mnt/wsl
tools           223G  111G  112G  50% /init
none            2.4G     0  2.4G   0% /dev
none            2.4G  8.0K  2.4G   1% /run
none            2.4G     0  2.4G   0% /run/lock
none            2.4G     0  2.4G   0% /run/shm
none            2.4G     0  2.4G   0% /run/user
tmpfs           2.4G     0  2.4G   0% /sys/fs/cgroup
drivers         223G  111G  112G  50% /usr/lib/wsl/drivers
lib             223G  111G  112G  50% /usr/lib/wsl/lib
drvfs           223G  111G  112G  50% /mnt/c
drvfs           366G   28G  339G   8% /mnt/d
drvfs           366G   20G  347G   6% /mnt/e

pwd

pwd stands for Print Working Directory. This command is contained in /usr/bin/pwd. It is frequently used to know the current directory location.

root@K-ASHIK-L4:/usr/bin# pwd
/usr/bin

clear

To clear the current terminal text, clear command is used. Just write clear and hit enter to clear the terminal text.

clear-terminal.gif

mkdir

To create directories mkdir is used.

root@K-ASHIK-L4:~/linux-command-practice# mkdir dir1
root@K-ASHIK-L4:~/linux-command-practice#
root@K-ASHIK-L4:~/linux-command-practice# ls -l
total 4
drwxr-xr-x 2 root root 4096 Jun 12 11:31 dir1

It can be also used to create multiple directories at a time:

root@K-ASHIK-L4:~/linux-command-practice# mkdir dir2 dir3 dir4
root@K-ASHIK-L4:~/linux-command-practice#
root@K-ASHIK-L4:~/linux-command-practice# ls -l
total 16
drwxr-xr-x 2 root root 4096 Jun 12 11:31 dir1
drwxr-xr-x 2 root root 4096 Jun 12 11:34 dir2
drwxr-xr-x 2 root root 4096 Jun 12 11:34 dir3
drwxr-xr-x 2 root root 4096 Jun 12 11:34 dir4

cd

cd command is used for changing working directory.

root@K-ASHIK-L4:~/linux-command-practice# pwd
/root/linux-command-practice
root@K-ASHIK-L4:~/linux-command-practice#
root@K-ASHIK-L4:~/linux-command-practice# cd dir1
root@K-ASHIK-L4:~/linux-command-practice/dir1#
root@K-ASHIK-L4:~/linux-command-practice/dir1#
root@K-ASHIK-L4:~/linux-command-practice/dir1# pwd
/root/linux-command-practice/dir1

Here before changing, working directory was /root/linux-command-practice and after changing working directory is /root/linux-command-practice/dir1

To go back to previous directory we can use cd ..

root@K-ASHIK-L4:~/linux-command-practice/dir1# pwd
/root/linux-command-practice/dir1
root@K-ASHIK-L4:~/linux-command-practice/dir1# cd ..
root@K-ASHIK-L4:~/linux-command-practice# pwd
/root/linux-command-practice

We can also go to any directory by mentioning it's path:

root@K-ASHIK-L4:~/linux-command-practice# ls
dir1  dir2  dir3  dir4
root@K-ASHIK-L4:~/linux-command-practice# cd dir2
root@K-ASHIK-L4:~/linux-command-practice/dir2#
root@K-ASHIK-L4:~/linux-command-practice/dir2# cd ../dir4
root@K-ASHIK-L4:~/linux-command-practice/dir4#

Here 4 directories in working directory - dir1 dir2 dir3 dir4. Firstly we move to dir2 directory and then from dir2 go to dir4.

touch

touch command is used for creating file(s) without content.

root@K-ASHIK-L4:~/linux-command-practice/touch# ls -l
total 0
root@K-ASHIK-L4:~/linux-command-practice/touch# touch file1.txt
root@K-ASHIK-L4:~/linux-command-practice/touch#
root@K-ASHIK-L4:~/linux-command-practice/touch# ls -l
total 0
-rw-r--r-- 1 root root 0 Jun 12 11:58 file1.txt

We can use multiple empty files in a single shot:

root@K-ASHIK-L4:~/linux-command-practice/touch# touch file2.txt logfile.log csvfile.csv
root@K-ASHIK-L4:~/linux-command-practice/touch#
root@K-ASHIK-L4:~/linux-command-practice/touch# ls -l
total 0
-rw-r--r-- 1 root root 0 Jun 12 12:00 csvfile.csv
-rw-r--r-- 1 root root 0 Jun 12 11:58 file1.txt
-rw-r--r-- 1 root root 0 Jun 12 12:00 file2.txt
-rw-r--r-- 1 root root 0 Jun 12 12:00 logfile.log

We can create file with any timestamp by following: touch -t YYYYMMDDHHMM fileName

root@K-ASHIK-L4:~/linux-command-practice/touch# touch -t 202105111212 time.txt
root@K-ASHIK-L4:~/linux-command-practice/touch#
root@K-ASHIK-L4:~/linux-command-practice/touch# ls -l
total 0
-rw-r--r-- 1 root root 0 Jun 12 12:00 csvfile.csv
-rw-r--r-- 1 root root 0 Jun 12 11:58 file1.txt
-rw-r--r-- 1 root root 0 Jun 12 12:00 file2.txt
-rw-r--r-- 1 root root 0 Jun 12 12:00 logfile.log
-rw-r--r-- 1 root root 0 May 11  2021 time.txt

cat

cat (concatenate) command is very frequently used command. It reads the contents of files and display as outputs.

Some of usages of cat command listed below:

  • Creating files with some content: Use Ctrl + D to exit after finishing content add.
root@K-ASHIK-L4:~/linux-command-practice/cat# cat > filewithcontent.txt
line1
line2
line3
line4
  • View the contents of a file:
root@K-ASHIK-L4:~/linux-command-practice/cat# cat filewithcontent.txt
line1
line2
line3
line4
root@K-ASHIK-L4:~/linux-command-practice/cat#
  • View contents from multiple files: Concatenates the files content sequentially and displays the output.
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# cat filewithcontent.txt anotherfile.log
line1
line2
line3
line4
anotherfile-line-1
anotherfile-line-2
anotherfile-line-3
anotherfile-line-4
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# cat anotherfile.log filewithcontent.txt
anotherfile-line-1
anotherfile-line-2
anotherfile-line-3
anotherfile-line-4
line1
line2
line3
line4
root@K-ASHIK-L4:~/linux-command-practice/cat#
  • Display line numbers in content:
root@K-ASHIK-L4:~/linux-command-practice/cat# cat -n filewithcontent.txt
     1  line1
     2  line2
     3  line3
     4  line4
root@K-ASHIK-L4:~/linux-command-practice/cat#
  • Replace one file's content with another: cat anotherfile.log > filewithcontent.txt Here content of file filewithcontent.txt replaced with content of anotherfile.log file.
root@K-ASHIK-L4:~/linux-command-practice/cat# cat filewithcontent.txt
line1
line2
line3
line4
root@K-ASHIK-L4:~/linux-command-practice/cat# cat anotherfile.log
anotherfile-line-1
anotherfile-line-2
anotherfile-line-3
anotherfile-line-4
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# cat anotherfile.log > filewithcontent.txt
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# cat filewithcontent.txt
anotherfile-line-1
anotherfile-line-2
anotherfile-line-3
anotherfile-line-4
root@K-ASHIK-L4:~/linux-command-practice/cat#
  • Append standard output of one file at the end of another file: cat filewithcontent.txt >> outputfile.log
root@K-ASHIK-L4:~/linux-command-practice/cat# cat outputfile.log
This is output file, you can append here
>


root@K-ASHIK-L4:~/linux-command-practice/cat# cat filewithcontent.txt >> outputfile.log
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# cat outputfile.log
This is output file, you can append here
>


anotherfile-line-1
anotherfile-line-2
anotherfile-line-3
anotherfile-line-4
root@K-ASHIK-L4:~/linux-command-practice/cat#
  • Append contents of multiples files and insert all output into a new file:
root@K-ASHIK-L4:~/linux-command-practice/cat# ls
logfile.log  outputfile.log  test1.log  test2.txt
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# cat test1.log
line-1
line-2
line-3
line-4
root@K-ASHIK-L4:~/linux-command-practice/cat# cat test2.txt
anotherfile-line-1
anotherfile-line-2
anotherfile-line-3
anotherfile-line-4
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# cat test1.log test2.txt > test3.log
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# ls
logfile.log  outputfile.log  test1.log  test2.txt  test3.log
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# cat test3.log
line-1
line-2
line-3
line-4
anotherfile-line-1
anotherfile-line-2
anotherfile-line-3
anotherfile-line-4
root@K-ASHIK-L4:~/linux-command-practice/cat#
  • Create a hidden file:
root@K-ASHIK-L4:~/linux-command-practice/cat# cat > .hiddenfile.txt
This is a hidden file
root@K-ASHIK-L4:~/linux-command-practice/cat#

mv

mv command is used to rename a file.

root@K-ASHIK-L4:~/linux-command-practice# ls
cat  dir1  dir100  dir2  dir3  grep  touch
root@K-ASHIK-L4:~/linux-command-practice#
root@K-ASHIK-L4:~/linux-command-practice# mv dir100 mv-command
root@K-ASHIK-L4:~/linux-command-practice#
root@K-ASHIK-L4:~/linux-command-practice# ls
cat  dir1  dir2  dir3  grep  mv-command  touch
root@K-ASHIK-L4:~/linux-command-practice#

rm

rm command is used to delete the files.

  • Ask permission to delete:
root@K-ASHIK-L4:~/linux-command-practice/cat# rm -i test2.txt
rm: remove regular file 'test2.txt'? y
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# ls
catdir  logfile.log.gz  numbers.txt  outputfile.log  test1.log  test3.log
  • Force delete: no permission asked
root@K-ASHIK-L4:~/linux-command-practice/cat# ls
catdir  logfile.log.gz  numbers.txt  outputfile.log  test1.log  test3.log
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# rm -f test1.log
root@K-ASHIK-L4:~/linux-command-practice/cat# ls
catdir  logfile.log.gz  numbers.txt  outputfile.log  test3.log
  • Delete all the files with extension .log:
root@K-ASHIK-L4:~/linux-command-practice/cat# ls
catdir  logfile.log.gz  numbers.txt  outputfile.log  test3.log
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# rm *log
root@K-ASHIK-L4:~/linux-command-practice/cat# ls
catdir  logfile.log.gz  numbers.txt
root@K-ASHIK-L4:~/linux-command-practice/cat#
  • Delete recursively files and directories:
root@K-ASHIK-L4:~/linux-command-practice/cat# ls
catdir  logfile.log.gz  numbers.txt  willbedeleted
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# rm -r *
root@K-ASHIK-L4:~/linux-command-practice/cat# ls

rmdir

rmdir commnd is used to delete empty directories and thros an error if directory is not empty.

root@K-ASHIK-L4:~# rmdir linux-command-practice
rmdir: failed to remove 'linux-command-practice': Directory not empty

root@K-ASHIK-L4:~/linux-command-practice/rmdir# ls
rmdir1  rmdir2
root@K-ASHIK-L4:~/linux-command-practice/rmdir# rmdir -v rmdir1
rmdir: removing directory, 'rmdir1'

Here -v option is used to get the verbose when deleting directories.

  • Remove all directory:
root@K-ASHIK-L4:~/linux-command-practice/rmdir# ls
rmdir2  rmdir3  rmdir4  rmdir5  rmdir6  rmdir7
root@K-ASHIK-L4:~/linux-command-practice/rmdir# rmdir -v *
rmdir: removing directory, 'rmdir2'
rmdir: removing directory, 'rmdir3'
rmdir: removing directory, 'rmdir4'
rmdir: removing directory, 'rmdir5'
rmdir: removing directory, 'rmdir6'
rmdir: removing directory, 'rmdir7'

cp

cp command is used to copy files from one source to destination.

root@K-ASHIK-L4:~/linux-command-practice/touch# ls
csvfile.csv  file1.txt  file2.txt  logfile.log  time.txt
root@K-ASHIK-L4:~/linux-command-practice/touch# cp /root/linux-command-practice/touch/*.txt /root/linux-command-practice/cat/
root@K-ASHIK-L4:~/linux-command-practice/touch# ls -l ../cat/
total 0
-rw-r--r-- 1 root root 0 Jun 12 16:53 file1.txt
-rw-r--r-- 1 root root 0 Jun 12 16:53 file2.txt
-rw-r--r-- 1 root root 0 Jun 12 16:53 time.txt
  • Using cp -r option we can copy directory with all contents:
root@K-ASHIK-L4:~/linux-command-practice# cp -r grep dir1
root@K-ASHIK-L4:~/linux-command-practice# cd dir1
root@K-ASHIK-L4:~/linux-command-practice/dir1# ls
grep
root@K-ASHIK-L4:~/linux-command-practice/dir1# cd grep/
root@K-ASHIK-L4:~/linux-command-practice/dir1/grep# ls
grepPracticeLog.log  grepfolder

ls

  • List files and directories:
root@K-ASHIK-L4:~/linux-command-practice/cat# ls
catdir  logfile.log  outputfile.log  test1.log  test2.txt  test3.log
  • List files or directories with their sizes:
root@K-ASHIK-L4:~/linux-command-practice/cat# ls -s
total 24
4 catdir  4 logfile.log  4 outputfile.log  4 test1.log  4 test2.txt  4 test3.log
  • List files in long format:
root@K-ASHIK-L4:~/linux-command-practice/cat# ls -l
total 24
drwxr-xr-x 2 root root 4096 Jun 12 13:00 catdir
-rw-r--r-- 1 root root 1184 Jun 12 12:26 logfile.log
-rw-r--r-- 1 root root  122 Jun 12 12:45 outputfile.log
-rw-r--r-- 1 root root   28 Jun 12 12:49 test1.log
-rw-r--r-- 1 root root   76 Jun 12 12:31 test2.txt
-rw-r--r-- 1 root root  104 Jun 12 12:50 test3.log

Here 1st column represents content permission, 2nd column represents no. of links , 3rd column owner, 4th group owner 5th size in bytes, 6th date modified and 7th is the file/directory name.

  • List files including hidden files:
root@K-ASHIK-L4:~/linux-command-practice/cat# ls -al
total 36
drwxr-xr-x 3 root root 4096 Jun 12 13:00 .
drwxr-xr-x 8 root root 4096 Jun 12 12:16 ..
-rw-r--r-- 1 root root   22 Jun 12 12:57 .hiddenfile.txt
drwxr-xr-x 2 root root 4096 Jun 12 13:00 catdir
-rw-r--r-- 1 root root 1184 Jun 12 12:26 logfile.log
-rw-r--r-- 1 root root  122 Jun 12 12:45 outputfile.log
-rw-r--r-- 1 root root   28 Jun 12 12:49 test1.log
-rw-r--r-- 1 root root   76 Jun 12 12:31 test2.txt
-rw-r--r-- 1 root root  104 Jun 12 12:50 test3.log
  • List files sort by size descending:
root@K-ASHIK-L4:~/linux-command-practice/cat# ls -lS
total 24
drwxr-xr-x 2 root root 4096 Jun 12 13:00 catdir
-rw-r--r-- 1 root root 1184 Jun 12 12:26 logfile.log
-rw-r--r-- 1 root root  122 Jun 12 12:45 outputfile.log
-rw-r--r-- 1 root root  104 Jun 12 12:50 test3.log
-rw-r--r-- 1 root root   76 Jun 12 12:31 test2.txt
-rw-r--r-- 1 root root   28 Jun 12 12:49 test1.log
  • List files sort by size ascending:
root@K-ASHIK-L4:~/linux-command-practice/cat# ls -lrS
total 24
-rw-r--r-- 1 root root   28 Jun 12 12:49 test1.log
-rw-r--r-- 1 root root   76 Jun 12 12:31 test2.txt
-rw-r--r-- 1 root root  104 Jun 12 12:50 test3.log
-rw-r--r-- 1 root root  122 Jun 12 12:45 outputfile.log
-rw-r--r-- 1 root root 1184 Jun 12 12:26 logfile.log
drwxr-xr-x 2 root root 4096 Jun 12 13:00 catdir
  • List files sort by date-time descending:
root@K-ASHIK-L4:~/linux-command-practice/cat# ls -lt
total 24
drwxr-xr-x 2 root root 4096 Jun 12 13:00 catdir
-rw-r--r-- 1 root root  104 Jun 12 12:50 test3.log
-rw-r--r-- 1 root root   28 Jun 12 12:49 test1.log
-rw-r--r-- 1 root root  122 Jun 12 12:45 outputfile.log
-rw-r--r-- 1 root root   76 Jun 12 12:31 test2.txt
-rw-r--r-- 1 root root 1184 Jun 12 12:26 logfile.log
  • List files sort by date-time ascending
root@K-ASHIK-L4:~/linux-command-practice/cat# ls -lrt
total 24
-rw-r--r-- 1 root root 1184 Jun 12 12:26 logfile.log
-rw-r--r-- 1 root root   76 Jun 12 12:31 test2.txt
-rw-r--r-- 1 root root  122 Jun 12 12:45 outputfile.log
-rw-r--r-- 1 root root   28 Jun 12 12:49 test1.log
-rw-r--r-- 1 root root  104 Jun 12 12:50 test3.log
drwxr-xr-x 2 root root 4096 Jun 12 13:00 catdir
  • List files in readable size format:
root@K-ASHIK-L4:~/linux-command-practice/cat# ls -lh
total 24K
drwxr-xr-x 2 root root 4.0K Jun 12 13:00 catdir
-rw-r--r-- 1 root root 1.2K Jun 12 12:26 logfile.log
-rw-r--r-- 1 root root  122 Jun 12 12:45 outputfile.log
-rw-r--r-- 1 root root   28 Jun 12 12:49 test1.log
-rw-r--r-- 1 root root   76 Jun 12 12:31 test2.txt
-rw-r--r-- 1 root root  104 Jun 12 12:50 test3.log
  • List all the files with extension .log in a readable size format and ascending of timestamp:
root@K-ASHIK-L4:~/linux-command-practice/cat# ls -lrth *.log
-rw-r--r-- 1 root root 1.2K Jun 12 12:26 logfile.log
-rw-r--r-- 1 root root  122 Jun 12 12:45 outputfile.log
-rw-r--r-- 1 root root   28 Jun 12 12:49 test1.log
-rw-r--r-- 1 root root  104 Jun 12 12:50 test3.log

wc

wc command stands for word count. It is used to find out number of lines, word count, byte and characters count in the files specified.

  • Print the no of lines in a file:
root@K-ASHIK-L4:~/linux-command-practice/cat# wc -l logfile.log
37 logfile.log
root@K-ASHIK-L4:~/linux-command-practice/cat#
  • Print the no of words in a file:
root@K-ASHIK-L4:~/linux-command-practice/cat# cat test1.log
line-1 colum2
line-2 column2
line-3 column2
line-4 column2
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# wc -w test1.log
8 test1.log
  • Display the count of characters:
root@K-ASHIK-L4:~/linux-command-practice/cat# wc -c test1.log
59 test1.log

uniq

uniq command is used to get the unique or duplicate lines from a file.

-d Display duplicate lines -u Display uniq lines -c Counts number of times each word has occurred in a file

root@K-ASHIK-L4:~/linux-command-practice/cat# cat test1.log
line-1 colum2
line-2 column2
line-3 column2
line-4 column2
line-4 column2
line-4 column2
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# uniq -c test1.log
      1 line-1 colum2
      1 line-2 column2
      1 line-3 column2
      3 line-4 column2
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# uniq -d test1.log
line-4 column2
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# uniq -u test1.log
line-1 colum2
line-2 column2
line-3 column2
root@K-ASHIK-L4:~/linux-command-practice/cat#

head

head command is used to view the first n lines of content.

root@K-ASHIK-L4:~/linux-command-practice/cat# head -3 logfile.log
"201000225","00000000",10100066
"201000228","00000000",10100069
"202000231","00000000",10200072
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# head -5 logfile.log
"201000225","00000000",10100066
"201000228","00000000",10100069
"202000231","00000000",10200072
"202000234","00000000",10200075
"203000240","00000000",10300078

tail

tail command is used to view the last n lines of content.

root@K-ASHIK-L4:~/linux-command-practice/cat# tail -2 logfile.log
"218000382","00000000",11800171
"218000383","00000000",11800174
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# tail -5 logfile.log
"216000369","00000000",11600162
"217000375","00000000",11700165
"217000378","00000000",11700168
"218000382","00000000",11800171
"218000383","00000000",11800174
root@K-ASHIK-L4:~/linux-command-practice/cat#
  • Print lines 26-30 using head and tail:
root@K-ASHIK-L4:~/linux-command-practice/cat# cat logfile.log | head -30 | tail -5
"213000339","00000000",11300141
"213000342","00000000",11300144
"214000348","00000000",11400147
"214000351","00000000",11400150
"215000357","00000000",11500153

cut

cut command is used to cut the required text from a file. It can cut the data on the columns and fields.

root@K-ASHIK-L4:~/linux-command-practice/cat# cat test1.log
line-1  colum2
line-2  column2
line-3  column2
line-4  column2
line-4  column2
line-4  column2
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# cut -c5 test1.log
-
-
-
-
-
-
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# cut -f2 test1.log
colum2
column2
column2
column2
column2
column2
root@K-ASHIK-L4:~/linux-command-practice/cat#

sort

  • Sort numbers
    root@K-ASHIK-L4:~/linux-command-practice/cat# cat numbers.txt
2
4
1
54
32
-4
9
100
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# sort -n numbers.txt
-4
1
2
4
9
32
54
100

  • Sort text files

    root@K-ASHIK-L4:~/linux-command-practice/cat# cat test3.log
line-1
line-2
line-3
line-4
anotherfile-line-1
anotherfile-line-2
anotherfile-line-3
anotherfile-line-4
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat#
root@K-ASHIK-L4:~/linux-command-practice/cat# sort test3.log
anotherfile-line-1
anotherfile-line-2
anotherfile-line-3
anotherfile-line-4
line-1
line-2
line-3
line-4
root@K-ASHIK-L4:~/linux-command-practice/cat#

  • Sort column 3 values in reverse order:

    root@K-ASHIK-L4:~/linux-command-practice/cat# sort -rk 3n logfile.log
"218000383","00000000",11800174
"218000382","00000000",11800171
"217000378","00000000",11700168
"217000375","00000000",11700165

grep

grep command is used for searching a required pattern in a file.

  • case insensitive search
root@K-ASHIK-L4:~/linux-command-practice/grep# grep -i "jmeter" grepPracticeLog.log
2. Download apache Jmeter latest version and extract
6. Then place extracted jar file into your jmeter /lib/ext directory.
7. Start JMETER and write API test script for following two cases: Here email must be generated from your jar file which you have performed in step 6 and 7.
root@K-ASHIK-L4:~/linux-command-practice/grep#

Here -i option will search log file for the string inside the "" case insensitively.

  • Count the no of occurrences 
root@K-ASHIK-L4:~/linux-command-practice/grep# grep -c "jmeter" grepPracticeLog.log
1
root@K-ASHIK-L4:~/linux-command-practice/grep# grep -ic "jmeter" grepPracticeLog.log
3
  • Search with whole word match:
root@K-ASHIK-L4:~/linux-command-practice/grep# grep -w "JMETER" grepPracticeLog.log
7. Start JMETER and write API test script for following two cases: Here email must be generated from your jar file which you have performed in step 6 and 7.
  • Display only the matched pattern:
root@K-ASHIK-L4:~/linux-command-practice/grep# cat grepPracticeLog.log
1. Setup Intellij IDEA
2. Download apache Jmeter latest version and extract
3. Create a java project in Intellij IDEA
4. Write a class GenerateRandomEmail and inside this class create a method getRandomEmail() which should return any random valid email.
5. Make a jar file from Intellij IDEA of your written project which you have performed in step 3 and 4.
6. Then place extracted jar file into your jmeter /lib/ext directory.
7. Start JMETER and write API test script for following two cases: Here email must be generated from your jar file which you have performed in step 6 and 7.

                Case - 1: User registration with valid email.
                Case - 2: User registration with already registered email.
root@K-ASHIK-L4:~/linux-command-practice/grep#
root@K-ASHIK-L4:~/linux-command-practice/grep#
root@K-ASHIK-L4:~/linux-command-practice/grep#
root@K-ASHIK-L4:~/linux-command-practice/grep# grep -o "Case" grepPracticeLog.log
Case
Case
root@K-ASHIK-L4:~/linux-command-practice/grep#
  • Print the lines not containing the string:
root@K-ASHIK-L4:~/linux-command-practice/grep# grep -v "email" grepPracticeLog.log
1. Setup Intellij IDEA
2. Download apache Jmeter latest version and extract
3. Create a java project in Intellij IDEA
5. Make a jar file from Intellij IDEA of your written project which you have performed in step 3 and 4.
6. Then place extracted jar file into your jmeter /lib/ext directory.
  • Search recursively using grep -R option into all the files and directories:

grep.png

gzip

gzip is used to make zip files

root@K-ASHIK-L4:~/linux-command-practice/touch# gzip csvfile.csv
root@K-ASHIK-L4:~/linux-command-practice/touch# ls
csvfile.csv.gz  file1.txt  file2.txt  logfile.log  time.txt
root@K-ASHIK-L4:~/linux-command-practice/touch# gzip -r *
root@K-ASHIK-L4:~/linux-command-practice/touch# ls
csvfile.csv.gz  file1.txt.gz  file2.txt.gz  logfile.log.gz  time.txt.gz
LinuxunixQAlinux-commandstesters