|
UNDERSTANDING BASH STARTUP FILES
The bash shell uses a variety of startup files, which are roughly analogous to the Autoexec.bat file on MS-DOS systems. What confuses more than a few Linux users is that bash (unlike MS-DOS) uses more than one startup file. Often, bash users have trouble figuring out which file they should use for new, automatically executed commands.
Here's a quick review of the startup files that bash can use, followed by a discussion of just when these startup files come into play. Note that the tilde (~) stands for your home directory.
The /etc/profile is the main startup file for bash. Because it is located in the /etc directory, which should be readable for all system users, it is used for commands that all users need. In contrast, a user's home directory contains one or more of the following bash startup files, which contain commands that apply only to the current user's bash session:
~/.bash_profile, ~/.bash_login, ~/.profile, ~/bash_rc, and ~/.bash_logout.
To understand how bash employs the various user startup files, you must understand the difference between a login shell and a nonlogin shell. A login shell is created when you log in to your Linux account. A nonlogin shell is created when you launch an additional bash shell within your user session, as you do when you open a terminal window in X.
When you start a login shell, bash consults the following files in the specified order:
/etc/profile
An A-Z Index of the Linux BASH command line
alias Create an alias
awk Find and Replace text within file(s)
break Exit from a loop
builtin Run a shell builtin
cal Display a calendar
case Conditionally perform a command
cat Display the contents of a file
cd Change Directory
chgrp Change group ownership
chmod Change access permissions
chown Change file owner and group
chroot Run a command with a different root directory
cksum Print CRC checksum and byte counts
clear Clear terminal screen
cmp Compare two files
comm Compare two sorted files line by line
command Run a command - ignoring shell functions
continue Resume the next iteration of a loop
cp Copy one or more files to another location
cron Daemon to execute scheduled commands
crontab Schedule a command to run at a later time
csplit Split a file into context-determined pieces
cut Divide a file into several parts
date Display or change the date & time
dc Desk Calculator
dd Data Dump - Convert and copy a file
declare Declare variables and give them attributes
df Report filesystem disk space usage
diff Display the differences between two files
diff3 Show differences among three files
dir Briefly list directory contents
dircolors Colour setup for `ls'
dirname Convert a full pathname to just a path
dirs Display list of remembered directories
du Estimate file space usage
echo Display message on screen
ed A line-oriented text editor (edlin)
egrep Search file(s) for lines that match an extended expression
eject Eject CD-ROM
enable Enable and disable builtin shell commands
env Display, set, or remove environment variables
expand Convert tabs to spaces
export Set an environment variable
exec Execute a command
expr Evaluate expressions
eval Evaluate several commands/arguments
factor Print prime factors
false Do nothing, unsuccessfully
fdformat Low-level format a floppy disk
fdisk Partition table manipulator for Linux
fgrep Search file(s) for lines that match a fixed string
find Search for files that meet a desired criteria
fmt Reformat paragraph text
fold Wrap input lines to fit in specified width
for Expand words, and execute commands
format Format disks or tapes
free Display memory usage
function Define Function Macros
gawk Find and Replace text within file(s)
getopts Parse positional parameters
grep Search file(s) for lines that match a given pattern
groups Print group names a user is in
gzip Compress or decompress named file(s)
hash Remember the full pathname of a name argument
head Output the first part of file(s)
history Command History
hostname Print or set system name
id Print user and group id's
if Conditionally perform a command
import Capture an X server screen and save the image to file
info Help info
install Copy files and set attributes
join Join lines on a common field
kill Kill a process
less Display output one screen at a time
let Perform arithmetic on shell variables
ln Make links between files
local Create variables
logname Print current login name
logout Exit a login shell
lpc Line printer control program
lpr Off line print
lprint Print a file
lprintd Abort a print job
lprintq List the print queue
lprm Remove jobs from the print queue
ls List information about file(s)
m4 Macro processor
man Help manual
mkdir Create new folder(s)
mkfifo Make FIFOs (named pipes)
mknod Make block or character special files
more Display output one screen at a time
mount Mount a file system
mtools Manipulate MS-DOS files
mv Move or rename files or directories
nice Change job scheduling priority
nl Number lines and write files
nohup Run a command immune to hangups
passwd Modify a user password
paste Merge lines of files
pathchk Check file name portability
popd Restore the previous value of the current directory
pr Convert text files for printing
printcap printer capability database
printenv Print environment variables
printf Format and print data
pushd Save and then change the current directory
pwd Print Working Directory
quota Display disk usage and limits
quotacheck Scan a file system for disk usage
quotactl Set disk quotas
ram ram disk device
read read a line from standard input
readonly Mark variables/functions as readonly
remsync Synchronize remote files via email
return Exit a shell function
rm Remove files
rmdir Remove folder(s)
rpm Remote Package Manager
rsync Synchronize file trees
screen Terminal window manager
sdiff Merge two files interactively
sed Stream Editor
select Accept keyboard input
seq Print numeric sequences
set Manipulate shell variables and functions
shift Shift positional parameters
shopt Shell Options
sleep Delay for a specified time
sort Sort text files
source Run commands from a file `.'
split Split a file into fixed-size pieces
su Run a command with substitute user and group id
sum Print a checksum for a file
symlink Make a new name for a file
sync Synchronize data on disk with memory
tac Concatenate and write files in reverse
tail Output the last part of files
tar Tape ARchiver
tee Redirect output to multiple files
test Evaluate a conditional expression
time Measure Program Resource Use
times User and system times
touch Change file timestamps
trap Run a command when a signal is set(bourne)
tr Translate, squeeze, and/or delete characters
true Do nothing, successfully
tsort Topological sort
tty Print filename of terminal on stdin
type Describe a command
ulimit Limit user resources
umask Users file creation mask
umount Unmount a device
unalias Remove an alias
uname Print system information
unexpand Convert spaces to tabs
uniq Uniquify files
units Convert units from one scale to another
unset Remove variable or function names
unshar Unpack shell archive scripts
until Execute commands (until error)
users Print login names of users currently logged in
uuencode Encode a binary file
uudecode Decode a file created by uuencode
v Verbosely list directory contents (`ls -l -b')
vdir Verbosely list directory contents (`ls -l -b')
watch Execute/display a program periodically
wc Print byte, word, and line counts
which Show full path of commands
while Execute commands
who Print all usernames currently logged in
whoami Print the current user id and name (`id -un')
yes Print a string until interrupted
.period Run commands from a file
### Comment / Remark
|
