I have implemented a linux bash shell. The code is in C.
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cd
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cd command changes your present working directory to the directory or path entered as an argument.
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Syntax : $ cd [directory_name / directory_path]
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Example :
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cd directory or cd dir1/dir2/dir3
myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ cd try myterminal@arka:~/home/arkasarkar/Desktop/CAOS/try $ myterminal@arka:~/home/arkasarkar $ cd Desktop/CAOS/try myterminal@arka:~/home/arkasarkar/Desktop/CAOS/try $ -
cd .. , changes to the parent directory of the current directory.
myterminal@arka:~/home/arkasarkar/Desktop/CAOS/try $ cd .. myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ -
cd ~, changes to the home directory
myterminal@arka:~/home/arkasarkar/Desktop/CAOS/try $ cd ~ myterminal@arka:~/home/arkasarkar $ -
cd , works just like cd ~ command
myterminal@arka:~/home/arkasarkar/Desktop/CAOS/try $ cd myterminal@arka:~/home/arkasarkar $ -
cd / , changes to the root directory
myterminal@arka:~/home/arkasarkar/Desktop $ cd / myterminal@arka:~/ $
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echo
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echo command is used to display line of text/string that are passed as an argument.
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Syntax : echo [option] [text]
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Example:
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echo “[text]”
myterminal@arka:~/home/arkasarkar $ echo "hello" hello myterminal@arka:~/home/arkasarkar $Arka Sarkar 2018222 -
echo -n [text] , -n omits a new trailing line after printing the text.
myterminal@arka:~/home/arkasarkar $ echo -n "hello" hellomyterminal@arka:~/home/arkasarkar $ -
echo * , displays all the files/folders
myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ echo * a.out cat.c date.c demo1.c history.txt ls.c makefile mkdir.c rm.c try
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history
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Displays all the commands previously executed.
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Syntax : history [option]
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Example: * history
myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ history history mkdir try try2 try3 mkdir t ls mkdir ry mkdir try ls ls ls -l ls -l -h -a cd demo ls cd ls ........ Cont..- history - c
- clears the history.
- history - c
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pwd
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Displays the present working directory
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Syntax : pwd
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Example : * pwd
myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ pwd current working directory :- /home/arkasarkar/Desktop/CAOS -
exit
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Exits the terminal
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Syntax : exit
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Example:
myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ exit -
ls
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Ls command displays all the files / folders in the present working directory
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Syntax : ls [option]
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Example:
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ls
myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ ls a.out cat.c date.c demo1.c history.txt ls.c makefile mkdir.c rm.c try -
ls -l , shows long format → all permisions, space , time modifed.
myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ ls -l total 60 -rwxr-xr-x 1 arkasarkar arkasarkar 17584 Sep 1 22:05 a.out -rw-rw-r-- 1 arkasarkar arkasarkar 1281 Sep 1 13:39 cat.c -rw-rw-r-- 1 arkasarkar arkasarkar 1142 Aug 30 16:08 date.c -rw-rw-r-- 1 arkasarkar arkasarkar 4944 Sep 1 22:05 demo1.c -rw-rw-r-- 1 arkasarkar arkasarkar 1039 Sep 1 22:18 history.txt -rw-rw-r-- 1 arkasarkar arkasarkar 757 Aug 30 01:58 ls.c -rw-r--r-- 1 arkasarkar arkasarkar 38 Aug 31 13:31 makefile -rw-rw-r-- 1 arkasarkar arkasarkar 1420 Aug 30 02:02 mkdir.c -rw-rw-r-- 1 arkasarkar arkasarkar 1144 Aug 30 16:03 rm.c drwxr-xr-x 2 arkasarkar arkasarkar 4096 Sep 1 21:12 try -
ls -lh, formats into human readable form.
total 60K -rwxr-xr-x 1 arkasarkar arkasarkar 18K Sep 1 22:05 a.out -rw-rw-r-- 1 arkasarkar arkasarkar 1.3K Sep 1 13:39 cat.c -rw-rw-r-- 1 arkasarkar arkasarkar 1.2K Aug 30 16:08 date.c -rw-rw-r-- 1 arkasarkar arkasarkar 4.9K Sep 1 22:05 demo1.c -rw-rw-r-- 1 arkasarkar arkasarkar 1.2K Sep 1 22:20 history.txt -rw-rw-r-- 1 arkasarkar arkasarkar 757 Aug 30 01:58 ls.c -rw-r--r-- 1 arkasarkar arkasarkar 38 Aug 31 13:31 makefile -rw-rw-r-- 1 arkasarkar arkasarkar 1.4K Aug 30 02:02 mkdir.c -rw-rw-r-- 1 arkasarkar arkasarkar 1.2K Aug 30 16:03 rm.c drwxr-xr-x 2 arkasarkar arkasarkar 4.0K Sep 1 21:12 try
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cat
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Read content from a file and displays it.
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Syntax : cat [filename]
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Example :
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cat [filename]
myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ cat del.txt Hello myterminal@arka:~/home/arkasarkar/Desktop/CAOS $
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date
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Displays current date
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Syntax : date [arg]
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Example:
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date
myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ date Sun Sep 1 22:31:43 IST 2019 -
date -R
myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ date -R Sun, 01 Sep 2019 22:31:54 +0530
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rm
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rm removes files or directories entered by the user.
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Syntax : rm [option] [filename]
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Example:
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rm [filename]
myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ rm del.txt -
rm -r [dir_name] , deletes a directory and its contents
myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ rm -r del -
rm -f [filename] , forcefully deletes a file if write protected.
myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ rm -f del.txt -
rm * , deletes all the files of the parent directory ( not the directories)
myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ rm * -
rm -r * , empties the parent directory
myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ rm -r *
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mkdir
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mkdir creates an empty directory in the present working directory
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Syntax : mkdir [dir_name]
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Example :
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mkdir [dir_name]
myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ mkdir hello myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ ls a.out date.c hello ls.c mkdir.c try cat.c demo1.c history.txt makefile rm.c -
mkdir [dir1_name] [dir2_name]
myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ mkdir hello hello2 myterminal@arka:~/home/arkasarkar/Desktop/CAOS $ ls a.out date.c hello history.txt makefile rm.c cat.c demo1.c hello2 ls.c mkdir.c try
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demo1.c is the main file. Compile it on the terminal using gcc demo1.c -o main and run the executable main as ./main commands.