Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: bash: read file line by line (lines have '\0') - not full line has read???
Top Forums Shell Programming and Scripting bash: read file line by line (lines have '\0') - not full line has read??? Post 302412917 by AskApache on Wednesday 14th of April 2010 02:13:32 AM
Old 04-14-2010
Very nice rowanthorpe.. I try to use bash builtins to spawn as few subshells and processes with fd's as possible.. always on a some server.

The pipe vs. redir question is one I've been trying to figure out too.. One of the best ways I've found to handle that is by using exec manually on fds. Consider this dos2unix clone and it's alternate way of determining input. N6=/dev/null personal pref..
Code:
dos2unixx ()
{
    [[ $# -eq 0 ]] && exec tr -d '\015\032' || [[ ! -f "$1" ]] && echo "Not found: $1" && return;
    for f in "$@";
    do
        [[ ! -f "$f" ]] && continue;
        tr -d '\015\032' < "$f" > "$f.t" && cmp "$f" "$f.t" > $N6 && rm -f "$f.t" || ( touch -r "$f" "$f.t" && mv "$f" "$f.b" && mv "$f.t" "$f" && rm -f "$f.b" ) >&$N6;
    done
}



And strangely enough, earlier today I was doing some work on my own builtin MORE command, basically I wanted a cat pager, this does pretty good but I've only had it a day..

Code:
shmore ()
{
    local l L M="`echo;tput setab 4&& tput setaf 7||echo -en  \"\e[34;01\"`   --- SH More ---   `tput sgr0||echo -e \"\e[m"`";
    L=1;
    while read l; do
        echo "${l}";
        ((L++));
        [ "$L" == "${LINES:-80}" ] && {
            L=1;
            read -p"$M" -u1
        };
    done
}


Finally, here's the shcat I use.. and if you do $ cat file | shcat | head, you get an error from the pipe issue you talk about. However you can work around it with an $ exec 2>&1 in the correct place.
Code:
shcat ()
{
    local l f e IFS="";
    e=0;
    if [ $# -eq 0 ]; then
        while read -r l; do
            echo "${l}";
        done;
    else
        for f in "$@";
        do
            if [ -r "${f}" ]; then
                while read -r l; do
                    echo "${l}";
                done < "${f}";
            else
                 < "${f}";
                e=1;
            fi;
        done;
        return $e;
    fi
}


Also, these 2 aliases I have created over time that work very well for stuff like this.

Code:
cata='exec 2>&1 cat -A'
cate='exec 2>&1 cat -v | sed s/\\^\\[/\\\\033/g'



---------- Post updated at 02:13 AM ---------- Previous update was at 02:08 AM ----------

Code:
seq -s`echo -ne \012` --format=%03g 0 128
seq -s`echo -ne \\012` --format=%03g 0 128
seq -s`echo -ne "\\012"` --format=%03g 0 128
seq -s`echo -ne "\\011"` --format=%03g 0 128
seq -s`echo -ne "\\010"` --format=%03g 0 128
seq -s`echo -ne "\\009"` --format=%03g 0 128
seq -s`echo -ne "\\002"` --format=%03g 0 128
seq -s`echo -ne "\\02"` --format=%03g 0 128
seq -s`echo -ne "\\2"` --format=%03g 0 128
seq -s`tput cols`` --format=%03g 0 128
seq -s`tput cols` --format=%03g 0 128
seq -s`tput sgr` --format=%03g 0 128
seq -s`tput eol` --format=%03g 0 128
seq -s`tput erase` --format=%03g 0 128
seq -s`tput bs` --format=%03g 0 128
seq -s`tput kbs` --format=%03g 0 128
seq -s'`tput kbs` ' --format=%03g 0 128
seq -s"`tput kbs` " --format=%03g 0 128
seq -s" `tput kbs` " --format=%03g 0 128
seq -s" `tput kbs`" --format=%03g 0 128
seq -s" `tput kbs` " --format=%03g 0 128


part of my shell session from earlier today... I was actually trying to make the separator be a null.. might be useful to know there are several ways to output nulls..


Code:
aa_print_ascii_chart ()
{
    local i;
    for i in `seq ${1:-0} ${2:-256}`;
    do
        echo -e "\\0$(( $i/64*100 + $i%64/8*10 + $i%8 ))";
    done
}

 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

cat file1 read line-per-line then grep -A 15 lines down in fileb

STEP 1 # Set variable FILE=/tmp/mainfile SEARCHFILE =/tmp/searchfile # THIS IS THE MAIN FILE. cat /tmp/mainfile Interface Ethernet0/0 "outside", is up, line protocol is up Hardware is i82546GB rev03, BW 100 Mbps Full-Duplex(Full-duplex), 100 Mbps(100 Mbps) MAC address... (6 Replies)
Discussion started by: irongeekio
6 Replies

2. Shell Programming and Scripting

Shell script to read a text file line by line & process it...

Hi , I am trying to write an shell, which reads a text file (from a location) having a list of numbers of strictly 5 digits only ex: 33144 Now my script will check : 1) that each entry is only 5 digits & numeric only, no alphabets, & its not empty. 2)then it executes a shell script called... (8 Replies)
Discussion started by: new_to_shell
8 Replies

3. Shell Programming and Scripting

how to read the contents of two files line by line and compare the line by line?

Hi All, I'm trying to figure out which are the trusted-ips and which are not using a script file.. I have a file named 'ip-list.txt' which contains some ip addresses and another file named 'trusted-ip-list.txt' which also contains some ip addresses. I want to read a line from... (4 Replies)
Discussion started by: mjavalkar
4 Replies

4. Shell Programming and Scripting

Read full line from file

hello all I'm writing a bash script and I need to read data from a file line by line The number of words of each line is not known and I want to check if anywhere in the line exists the substring www..That substring is a string by itself or a substring of other strings.So what I tried so far... (4 Replies)
Discussion started by: vlm
4 Replies

5. Shell Programming and Scripting

Need a program that read a file line by line and prints out lines 1, 2 & 3 after an empty line...

Hello, I need a program that read a file line by line and prints out lines 1, 2 & 3 after an empty line... An example of entries in the file would be: SRVXPAPI001 ERRO JUN24 07:28:34 1775 REASON= 0000, PROCID= #E506 #1065: TPCIPPR, INDEX= 003F ... (8 Replies)
Discussion started by: Ferocci
8 Replies

6. Shell Programming and Scripting

Bash script to read a file from particular line till required line and process

Hi All, Am trying to write wrapper shell/bash script on a utility tool for which i need to pass 2 files as arugment to execute utility tool. Wraper script am trying is to do with above metion 2 files. utility tool accepts : a. userinfo file : which contains username b. item file : which... (2 Replies)
Discussion started by: Optimus81
2 Replies

7. Shell Programming and Scripting

How to read file line by line and compare subset of 1st line with 2nd?

Hi all, I have a log file say Test.log that gets updated continuously and it has data in pipe separated format. A sample log file would look like: <date1>|<data1>|<url1>|<result1> <date2>|<data2>|<url2>|<result2> <date3>|<data3>|<url3>|<result3> <date4>|<data4>|<url4>|<result4> What I... (3 Replies)
Discussion started by: pat_pramod
3 Replies

8. Shell Programming and Scripting

[BASH] read 'line' issue with leading tabs and virtual line breaks

Heyas I'm trying to read/display a file its content and put borders around it (tui-cat / tui-cat -t(ypwriter). The typewriter-part is a 'bonus' but still has its own flaws, but thats for later. So in some way, i'm trying to rewrite cat using bash and other commands. But sadly it fails on... (2 Replies)
Discussion started by: sea
2 Replies

9. Shell Programming and Scripting

With script bash, read file line per line starting at the end

Hello, I'm works on Ubuntu server My goal : I would like to read file line per line, but i want to started at the end of file. Currently, I use instructions : while read line; do COMMAND done < /var/log/apache2/access.log But, the first line, i don't want this. The file is long... (5 Replies)
Discussion started by: Fuziion
5 Replies

10. Shell Programming and Scripting

Read the file line by line and do something with lines

I have a file file_name_O.txt The file can have different number of other files names or nothing I will check cnt=`wc -l file_name_0.txt` if ;then exit 1 fi Now I have to start checking file names, i.e. read txt file line by line. If amount of ,lines equal 1, I can... (4 Replies)
Discussion started by: digioleg54
4 Replies
All times are GMT -4. The time now is 11:59 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy