shell scripts

Coldfan20 · 08-08-2007, 05:35 PM

Im trying to write a shell script and write the data to another file and i can not find the syntax any where does any one know the syntax to help me out thanks

pixellany · 08-08-2007, 05:47 PM

What books are you using? Two to start with are:
Bash Guide for Beginners, Machtelt Garrels---free at tldp.org
Classic Shell scripting from O'Reilly (might be available in their new free online service.)

Here is one example of reading and writing files using redirection.

This reads data from file1, replaces all occurrences of "yes" with "no", and writes the data to file2:

sed 's/yes/no/g' <file1 >file2
This does exactly the same thing:
cat file1 | sed 's/yes/no/g' >file2

Coldfan20 · 08-08-2007, 05:54 PM

i want it to write to the file right after all the information is input, with the code that you gave me my script should look like this i beleive am i right?

#!/bin/bash
echo “enter employee name”
read employee name
echo “age”
read age
echo “dept num”
read dept num
cat file1 | sed 's/yes/no/g' >employee.db

Quote:

Originally Posted by pixellany

What books are you using? Two to start with are:
Bash Guide for Beginners, Machtelt Garrels---free at tldp.org
Classic Shell scripting from O'Reilly (might be available in their new free online service.)

Here is one example of reading and writing files using redirection.

This reads data from file1, replaces all occurrences of "yes" with "no", and writes the data to file2:

sed 's/yes/no/g' <file1 >file2
This does exactly the same thing:
cat file1 | sed 's/yes/no/g' >file2

chrism01 · 08-08-2007, 06:40 PM

You can't have spaces in variable names, use underscores.
Read this page: http://tldp.org/LDP/abs/html/io-redirection.html
Also: http://tldp.org/LDP/abs/html/x16239.html#USINGEXECREF

pixellany · 08-08-2007, 08:37 PM

Quote:

Originally Posted by Coldfan20

i want it to write to the file right after all the information is input, with the code that you gave me my script should look like this i beleive am i right?

#!/bin/bash
echo “enter employee name”
read employee name
echo “age”
read age
echo “dept num”
read dept num
cat file1 | sed 's/yes/no/g' >employee.db

I only gave you an example.....not a literal command. As you have it stated above, the last line will do nothing. (eg "file1" does not exist)

Let's assume you have successfully created a variable "dept_num". To write that variable to your employee.db file, you would do:
echo $dept_num >employee.db
Now to add the contents of age, you would do:
echo $age >>employee.db
Note that >> = append

The best way to learn this stuff is the try one command at time in the interactive mode. Once you know how a command works, then you can put it in your script.

cfaj · 08-08-2007, 10:50 PM

Quote:

Originally Posted by pixellany

I only gave you an example.....not a literal command. As you have it stated above, the last line will do nothing. (eg "file1" does not exist)

It doesn't do nothing; it will give you an error message.

Quote:

Let's assume you have successfully created a variable "dept_num". To write that variable to your employee.db file, you would do:
echo $dept_num >employee.db
Now to add the contents of age, you would do:
echo $age >>employee.db
Note that >> = append

Better would be to group the commands into a single compound command (using braces) and a single redirect:
Code:
{
  echo "$dept_num"
  echo "$age"
} > employee.db
And note the quoting of the variables. This prevents filename expansion if there are any wildcard characters, and preserves spacing.