Regular Expressions


 
Thread Tools Search this Thread
Top Forums UNIX for Advanced & Expert Users Regular Expressions
# 1  
Old 05-15-2008
Regular Expressions

Hi,
below is a piece of code written by my predecessor at work.
I'm kind of a newbie and am trying to figure out all the regular expressions in this piece of code.
It is really a tough time for me to figure out all the regular expressions.

Please shed some light on the regular expressions in this code

ssh_list() {
typeset userAtHost="$1"
typeset dir="${2-.}"
typeset wild="${3-*}"

info "SSH list: $userAtHost $src $dst"

if [ "$REGION" != prod ] ;then
userAtHost=$LOGNAME@localhost
fi

# Save, disable, and restore the verbose flag - any
# verbose output would look like errors.
typeset verbose="$(set -o |sed -n 's/^verbose *//p')"
set +v
typeset msgs="$(sftp $userAtHost 2>&1 <<EOF
cd $dir
ls
EOF)"
if [ "$verbose" = on ] ;then
set -v
fi

# Strip the "Connecting to host..." line, prompts, blank lines
# and login banners. What's left should only be error messages.
typeset errs="$(echo "$msgs" |
sed -e '/^Connecting to .*\.\.\.$/d' \
-e 's/sftp > //g' \
-e '/^[ ]*$/d' \
-e '/^#/d' \
-e '/^[-dDlbcps][-rwxsStTlL]\{9\}+\{0,1\} /d')"

if [ "$errs" != "" ] ;then
error "$errs"
return 1
fi

echo "$msgs" |
while read line
do
case "$line" in -*\ $wild)
echo ${line##* }
;;esac
done

return 0
}

I'd like some explanation of these lines.... gurus please shed some light.

Thank you for your time.
Ram
# 2  
Old 05-16-2008
Quote:
Originally Posted by ramky79
# Save, disable, and restore the verbose flag - any
# verbose output would look like errors.
typeset verbose="$(set -o |sed -n 's/^verbose *//p')"
set +v
This one even has a comment to explain what it does. It disables verbose debugging (disables set -v if set), remembering the previous state of the flag in the verbose variable.

Quote:
# Strip the "Connecting to host..." line, prompts, blank lines
# and login banners. What's left should only be error messages.
typeset errs="$(echo "$msgs" |
sed -e '/^Connecting to .*\.\.\.$/d' \
-e 's/sftp > //g' \
-e '/^[ ]*$/d' \
-e '/^#/d' \
-e '/^[-dDlbcps][-rwxsStTlL]\{9\}+\{0,1\} /d')"
Again, the comments are probably better than any detailed attempt at going through the individual regular expressions. Any "Connecting to ..." line is removed. Any sftp> prompt is removed. Any empty line is removed. Any line beginning with a hash sign is removed. The last one looks vaguely like it's intended to remove directory listing output.

Quote:
echo "$msgs" |
while read line
do
case "$line" in -*\ $wild)
echo ${line##* }
;;esac
done
This prints any line from $msgs which matches a dash, followed by anything, followed by a space, followed by the value of the variable $wild, with everything up to the last space trimmed away. (None of this involves any regular expressions, strictly speaking; both the case statement and the ${var##subst} interpolation work with glob patterns.)

$wild is defined up at the beginning of the function as either positional argument $3 or (if that is empty) an asterisk, which matches anything in glob wildcard notation.
# 3  
Old 05-19-2008
Mastering Regular Expressions

Get yourself a copy of Mastering Regular Expressions by Jeffrey Friedl. You'll benefit quite a bit from it.

Shawn
# 4  
Old 05-21-2008
Thank you era and Shawn

The script however works fine on sunSSH
It does not work on an OPEN SSH, I tries to tweak in a little more with the regular expressions... but it still does not help.
Any idea how to overcome this problem.
when I execute the same script on OPEN SSH box here is the error I get.
If I logon interactively from the OPEN SSH box and execute the commands one by one, they work. when they are placed in a script the script doesnot work.any help is appreciated.

INFO: SSH list: user@host outgoing x001_ameint_*.zip
ERROR: #^M
ERROR: #==============================================^M
ERROR: #Bowne Marketing & Business Communications^M
ERROR: #SFTP Server (PCN)^M
ERROR: #==============================================^M
ERROR: #^M
ERROR: ^M
ERROR: sftp> sftp> drwx------ 0 0 0 0 May 21 15:25 .
ERROR: drwx------ 0 0 0 0 Mar 17 11:58 ..
ERROR: drwx------ 0 0 0 0 May 21 15:59 archive
ERROR: -rw------- 0 0 0 4152 May 9 11:44 x001_REPORTS_ameint_AIGODN00857.zip
ERROR: -rw------- 0 0 0 42138973 May 19 14:16 x001_ameint_BP010F0010_00002_003.zip.done
ERROR: -rw------- 0 0 0 377449320 Apr 14 14:20 x001_ameint_BP010F0010_00264_001.zip.done
ERROR: -rw------- 0 0 0 637950 May 21 13:40 x001_ameint_abc.zip
ERROR: -rw------- 0 0 0 408 May 21 13:49 x001_ameint_def.zip
ERROR: -rw------- 0 0 0 408 May 21 13:53 x001_ameint_xyz.zip
ERROR: sftp> Invalid command.^M
ERROR: sftp>

here are my tweaked regular expressions:
ssh_list() {
typeset userAtHost="$1"
typeset dir="${2-.}"
typeset wild="${3-*}"

info "SSH list: $userAtHost $dir $wild"

# Save, disable, and restore the verbose flag - any
# verbose output would look like errors.
typeset verbose="$(set -o |sed -n 's/^verbose *//p')"
set +v
typeset msgs="$(sftp $userAtHost 2>&1 <<EOF
cd $dir
ls -l
EOF)"

echo $msgs > TEXT.dat

if [ "$verbose" = on ] ;then
set -v
fi

# Strip the "Connecting to host..." line, prompts, blank lines
# and login banners. What's left should only be error messages.
typeset errs="$(echo "$msgs" |
sed -e '/^Connecting to .*\.\.\.$/d' \
# -e '/^ERROR: unable to initialize mechanism library [/usr/lib/gss/gl/mech_krb5.so]/d' \
-e '/ERROR: //g' \
-e 's/^$//g' \
-e 's/sftp> //g' \
-e '/^[ ]*$/d' \
-e '/^#/d' \
-e '/^[-dDlbcps][-rwxsStTlL]\{9\}+\{0,1\} /d')"

if [ "$errs" != "" ] ;then
error "$errs"
return 1
fi

echo "$msgs" |
while read line
do
case "$line" in -*\ $wild)
echo ${line##* }
;;esac
done

return 0
}


ssh_sendrecv() {
typeset op="$1"
typeset userAtHost="$2"
typeset src="$3"
typeset dst="$4"

info "SSH transfer: $op $userAtHost $src $dst"

#if [ "$REGION" != prod ] ;then
#userAtHost=$LOGNAME@localhost
#fi


# Save, disable, and restore the verbose flag - any
# verbose output would look like errors.
typeset verbose="$(set -o |sed -n 's/^verbose *//p')"
set +v
typeset msgs="$(sftp $userAtHost 2>&1 <<EOF
$op $src $dst
EOF)"
if [ "$verbose" = on ] ;then
set -v
fi

# Strip the "Connecting to host..." line, prompts, blank lines
# and login banners. What's left should only be error messages.
typeset errs="$(echo "$msgs" |
sed -e '/^Connecting to .*\.\.\.$/d' \
-e 's/^$//g' \
-e 's/sftp> //g' \
-e '/^[ ]*$/d' \
-e '/^#/d')"

if [ "$errs" != "" ] ;then
error "$errs"
return 1
fi

return 0
}
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Regular expressions

I need to pick a part of string lets stay started with specific character and end with specific character to replace using sed command the line is like this:my audio book 71-skhdfon1dufgjhgf8.wav' I want to move the characters beginning with - end before. I have different files with random... (2 Replies)
Discussion started by: XP_2600
2 Replies

2. Shell Programming and Scripting

Regular Expressions

I am new to shell scripts.Can u please help me on this req. test_user = "Arun" if echo "test_user is a word" else echo "test_user is not a word" (1 Reply)
Discussion started by: chandrababu
1 Replies

3. Shell Programming and Scripting

Help with regular expressions

I have a file that I'm trying to find all the cases of phone number extensions and deleting them. So input file looks like: abc x93825 def 13234 x52673 hello output looks like: abc def 13234 hello Basically delete lines that have 5 numbers following "x". I tried: x\(4) but it... (7 Replies)
Discussion started by: pxalpine
7 Replies

4. Shell Programming and Scripting

Regular Expressions

#!/usr/bin/perl $word = "one last challenge"; if ( $word =~ /^(\w+).*\s(\w+)$/ ) { print "$1"; print "\n"; print "$2"; } The output shows that "$1" is with result one and "$2" is with result challenge. I am confused about how this pattern match expression works step by step. I... (8 Replies)
Discussion started by: DavidHe
8 Replies

5. UNIX for Dummies Questions & Answers

Regular expressions

In regular expressions with grep(or egrep), ^ works if we want something in starting of line..but what if we write ^^^ or ^ for pattern matching??..Hope u all r familiar with regular expressions for pattern matching.. (1 Reply)
Discussion started by: aadi_uni
1 Replies

6. Shell Programming and Scripting

regular expressions

Hello, Let say I have a string with content "Free 100%". How can extract only "100" using ksh? I would this machanism to work if instead of "100" there is any kind of combination of numbers(ex. "32", "1238", "1"). I want to get only the digits. I have written something like this: ... (4 Replies)
Discussion started by: whatever
4 Replies

7. UNIX for Dummies Questions & Answers

regular expressions

Hi Gurus, I need help with regular expressions. I want to create a regular expression which will take only alpha-numeric characters for 7 characters long and will throw out an error if longer than that. i tried various combinations but couldn't get it, please help me how to get it guys. ... (2 Replies)
Discussion started by: ragha81
2 Replies

8. Shell Programming and Scripting

Help with regular expressions

I have following content in the file CancelPolicyMultiLingual3=U|PC3|EN RestaurantInfoCode1=U|restID1|1 ..... I am trying to use following matching extression \|(+) to get this PC3|EN restID1|1 Obviously it does not work. Any ideas? (13 Replies)
Discussion started by: arushunter
13 Replies

9. Shell Programming and Scripting

regular expressions

Hi, can anyone advise me how to shorten this: if || ; then I tried but it dosent seem to work, whats the correct way. Cheers (4 Replies)
Discussion started by: jack1981
4 Replies

10. Programming

regular expressions in c++

How do I use the regular expressions in c++? (2 Replies)
Discussion started by: szzz
2 Replies
Login or Register to Ask a Question