EmbLogic » shell scripting

ls – list command

Ankur Garg — Wed, 10 Feb 2016 17:20:32 +0000

ls – list command
=================
- ls means list directory content
- Prototype :
ls [OPTION] … [FILE] …
- Exit status
It returns 0 ,on success
Returns 1 in case of minor problems (eg. cannot access subdirectory)
returns 2 in case of serious trouble (eg. Cannot access command line argument)
- For specific listing you can use *
eg.1) For listing all files starting with a use :
ls a*
2) for listing all .c files use :
ls *.c
3) for listing all .c files starting with a use :
ls a*.c
- Some common options are :
i) -a –all –> Do not ignore enteries starting with .
Use this to view swap or temporary files.
ii) -l –> long listing format
iii) -r –) Reverse order sort (by name) and list
iv) -s –size –> Print allocated size of each file in blocks
v) -S –> Sort by file size
vi) -t –> Sort by modification time, newest first
vii) -U –> Do not sort; list enteries in directory order
viii) -X –> Sort alphabetically by entry extension.
ix) -F –> to distinguish files from directories (Puts / in directory and * with executable files)
x) -R –> It shows files that are contained in directory. It continued to dirrectory in a directory and so on.

- In fedora for long lsting use command :

How to change default prompt in BASH shell

Ankur Garg — Sun, 07 Feb 2016 15:46:40 +0000

To change default prompt :-
========================
- We can change default prompt by assigning the character to it.
- Each character have a specific meaning.

BASH Shell Prompt Characters :-
Character Description
\a Bell Character
\d Date in format “Day Month Date”
\e ASCII escape character
\h Local hostname
\H Fully qualified domain hostname
\j Number of jobs currently managed by the shell
\l Basename of the shell’s terminal device name
\n ASCII newline character
\r ASCII carriage return
\s Name of the shell
\t Current time in 24-hour HH:MM:SS format
\T Current time in 12-hour HH:MM:SS format
\@ Current time in 12-hour am/pm format
\u Username of current user
\v Version of BASH shell
\V Release level of bash shell
\w Current working directory
\W Basename of current working directory
\# Command number of this command
\$ A dollar sign if normal user, #(Pound) for root user
/nnn Character corresponding to value nnn
\\ Backslash
\[ Begins a control code sequence
/] Ends a control code sequence

eg.
[ankur@(none) ~]$ PS1 = “[\t][\u]$”
[15:20:30][ankur]$

Command line Prompt – PS1, PS2

Ankur Garg — Sun, 07 Feb 2016 15:44:42 +0000

Command line Prompt
===================
Environmental variables that controls Command line Prompt
PS1 : Controls the format of default command line prompt.
PS2 : Controls the format of second-tier command line prompt.
PS3 : Controls the format of tertiary command line prompt.

- Shell uses default PS1 prompt for initial data entry into shell.
- If we enter a command that requires additional information, shell displays second-tier prompt specified by PS2 .
- To display current settings for prompt use command :
echo $PS1
echo $PS2
- PS3 is used only in shell scripts.

scripting problem

saurabh.aggarwal — Fri, 30 Mar 2012 15:02:20 +0000

I am trying to make a Makefile which can accept an a c file name as an argument to be used as a variable in my script so that i can use it with any of my c files for compilation .
the content of Makefile as follows..

#!/bin/bash

x=$1
exec: ${x}.o
gcc -o exec ${x}.o
${x}.o: ${x}.c
gcc -c ${x}.o ${x}.c

it is not executing properly as the final executable file is not exec but the with the same name as that of the c file name..i think its using the default makefile to create the executable file .
am i doing it right ?????what is the right make command (to be given) to execute this script…