Linux Programming: Difference between revisions

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== Conditions ==
== Conditions ==
<pre>
if [ -f fred.c ]
then
...
fi
if [ -f fred.c ]; then
...
fi
</pre>
Arithmetic comparison
<pre>
expr1 -eq expr2
expr1 -ne expr2
expr1 -gt expr2
expr1 -ge expr2
expr1 -lt expr2
expr1 -le expr2
! expr
</pre>
File conditionals
<pre>
-d file  ==> True if the file is a directory
-e file  ==> True if the file exists
-f file  ==> True if the file is a regular file
-r file  ==> True if the file is readable
-s file  ==> True if the file has non-zero size
-w file  ==> True if the file is writable
-x file  ==> True if the file is executable
</pre>
== Control Structures ==
== Control Structures ==
== Functions ==
== Functions ==

Revision as of 10:04, 21 April 2014

Shell Programming

Variables

food=Banana
echo $food
food="Apple"
echo $food
$HOME
$PATH
$0 -- name of the shell script
$# -- number of parameters passed
$$ process ID of the shell script, often used inside a script for generating unique temp filenames
$1, $2, .... -- parameters given to the script
$* -- list of all the parameters, in a single variable
$@ -- subtle variation on $*

Conditions

if [ -f fred.c ]
then
...
fi

if [ -f fred.c ]; then
...
fi

Arithmetic comparison

expr1 -eq expr2
expr1 -ne expr2
expr1 -gt expr2
expr1 -ge expr2
expr1 -lt expr2
expr1 -le expr2
! expr

File conditionals

-d file  ==> True if the file is a directory
-e file  ==> True if the file exists
-f file  ==> True if the file is a regular file
-r file  ==> True if the file is readable
-s file  ==> True if the file has non-zero size
-w file  ==> True if the file is writable
-x file  ==> True if the file is executable

Control Structures

Functions

Commands

Command Execution

Debugging Scripts

Working with Files

UNIX environment

Logging

Resources and Limits

Curses

A technique between command line and full GUI.

Example: vi.

Data Management

Development Tools

make and Makefiles

Writing a Manual Page

Distributing Software

The patch Program

Debugging

gdb

Processes and Signals

POSIX threads

Inter-process Communication: Pipes

Sockets