article in Tech programming

Bash and batch programming

Hidden features of Windows batch files - Stack Overflow - windows cmd.exe has many hidden features, this page has most of it covered...

Wanna loop over files in bash and perform a cmd on those files?

# (where $i is replaced by the name of the file)
for i in ./*.conf; do cmd -c $i; done

or using find

# (where {} is replaced by the name of the file)
find . -name *.conf -exec cmd {} \;

I usually opt. for the find version because it seems to be more capable.

Then if you are on windows, you don't get find and you can't use the bash syntax of course.... So use, forfiles! What a gem. Gives you access to filename without extension and do things differently if you are testing for files or folders.
forfiles is very powerful.
O'Reilly -- Ten Essential Windows 2000 Commands

Cutting up file/path strings in bash

Of course you could use the programs 'dirname' or 'basename'...but you can also do it using bash regex...

Get directory portion of path: dirportion = ${path%/*}
Get the filename of path: filename = ${path##*/}
Get the basename of the file (without extension): basename = ${path%%.*}
Get the extension of the path: ext = ${file#*.}

These examples are based on these operations:

${variable%pattern}: Trim the shortest match from the end
${variable##pattern}: Trim the longest match from the beginning
${variable%%pattern}: Trim the longest match from the end
${variable#pattern}: Trim the shortest match from the beginning

bash String Manipulations Issue 18

Wanna make a CGI script in bash?

If you ever need to quickly code up a bash CGI script, use bashlib.

Great programming info:
Advanced Bash-Scripting Guide
Quick syntax guide
If

if [ expression ]
then
   commands
elif [ expression2 ]
then
   commands
else
   commands
fi

While

#This program lists the parameters that were passed to the program, along with the parameter number.

count=1
while [ -n "$*" ]
do
   echo "This is parameter number $count $1"
   shift
   count='expr $count + 1'
done

Case statement

case $1 in
-i)
   count='grep ^i $2 | wc -l'
   echo "The number of lines in $2 that start with an i is $count"
   ;;
-e)
   count='grep ^e $2 | wc -l'
   echo "The number of lines in $2 that start with an e is $count"
   ;;
*)
   echo "That option is not recognized"
   ;;
esac

For

# In this form, the for statement executes once for each item in the list. 
# This list can be a variable that contains several words separated by spaces, 
# or it can be a list of values that is typed directly into the statement. Each 
# time through the loop, the variable var1 is assigned the current item in the 
# list, until the last one is reached.
for var1 in list
do
   commands
done

How to run a command for each line of a file using sed.
sed is your friend.

for i in `sed -e 's/,.*$//g' < upgrade/4.1.9-4.1.11/file.lst`; do chmod 666 $i ; done

Find and replace using find and sed

find ./ -type f -exec sed -i ’s/string1/string2/’ {} \;

Display ls tree || dirtree in unix

Unix Tree / Linux Tree • Display Structure of Directory Hierarchy -

ls -R | grep ":$" | sed -e 's/:$//' -e 's/[^-][^\/]*\//--/g' -e 's/^/   /' -e 's/-/|/'

tree (Unix) - Wikipedia
The Tree Command for Linux Homepage

Created: 2005-03-27 03:08:28 Modified: 2013-10-18 02:06:51