Ask General Programming Questions Not Worth Their Own Thread

The Something Awful Forums > Discussion > Serious Hardware/Software Crap > The Cavern of COBOL > Ask General Programming Questions Not Worth Their Own Thread

axolotl farmer: May 17, 2007; Now I'm going to sing the Perry Mason theme

I'm writing a bash script that involves a long series of pipes. I also want to make it readable.

Is there a simple way to put these on multiple lines and making bash treat it as one single line of input?

code:

from
command 'args' $1 |anothercommand|yetanother|...|nthcommand

to  
command 'args' $1 
|anothercommand
|yetanother
|...|
|...nthcommand

Sort of the opposite of a semicolon!

# ¿ Feb 28, 2008 17:28

Adbot: ADBOT LOVES YOU

# ¿ Apr 29, 2024 12:35

axolotl farmer: May 17, 2007; Now I'm going to sing the Perry Mason theme

6174 posted:

What you are looking for is called a line continuation character. In the case of bash it is \

Oh yes it is. My error was caused by something else. :blush:

# ¿ Feb 28, 2008 18:11

axolotl farmer: May 17, 2007; Now I'm going to sing the Perry Mason theme

Here's my very ugly take on it!

echo "16(100%)" |sed 's/[()%]/ /g'|awk '{print $2}'

# ¿ Feb 28, 2008 20:28

axolotl farmer: May 17, 2007; Now I'm going to sing the Perry Mason theme

I'm making a bash script where I need to echo $VARIABLE number of something on a line, let's say Xs.

Like this, the unknown command is [?]:

alice=5
bob=7
echo "Alice [?]"
echo "Bob [?]"

...and get this output:

Alice XXXXX
Bob XXXXXXX

# ¿ Mar 7, 2008 20:53

axolotl farmer: May 17, 2007; Now I'm going to sing the Perry Mason theme

Plastic Jesus posted:

I totally misread this and thought that you wanted to print the number of characters in a string. Which is actually awesome because I learned how to find out the length of a string in bash (it's ${#var_name} btw).

All that you need to do is
code:
alice=5
for(( i = 0; i < alice; i++ ))
do
   echo -n "X"
done
echo

That was exactly what I needed. That get lenght of a string thing will be very useful for me too. I did that by

stringlength=`echo $string | wc -l`

# ¿ Mar 9, 2008 16:25

axolotl farmer: May 17, 2007; Now I'm going to sing the Perry Mason theme

In bash, is there a way to redirect stdout to a command that works on files?

I have a list that I'd like to compare to another list using comm. One of the lists is created by a [long tangle of seds, awks and greps], while the other is a file (mylist). The command comm only takes input as files.

Do I have to go by a temp file, or is there some way to get comm to work with the stdout?

from:
[long tangle of seds, awks and greps] >tempfile
comm tempfile mylist

to:
comm mylist [long tangle of seds, awks and greps]

# ¿ Mar 14, 2008 22:30

axolotl farmer: May 17, 2007; Now I'm going to sing the Perry Mason theme

floWenoL posted:

Yes. You want "comm mylist <(long tangle of seds awks and greps)". Under the hood, bash replaces <(...) with something like /dev/fd/XXX which is the dev path to the stdout of the process.

Thank you! This is extremely useful.

I haven't seen this in any of the many bash tutorials/tips/tricks I've seen online. This is as useful as 2>&1 !

# ¿ Mar 17, 2008 19:42

Adbot: ADBOT LOVES YOU

# ¿ Apr 29, 2024 12:35

axolotl farmer: May 17, 2007; Now I'm going to sing the Perry Mason theme

This is a bash/shellscript question:

I have file with lots of DNA sequences in them. Missing letters are replaced by -s. They look like this:
-----AACGCT--TTGGT-- -GG-TAACGCT--TTGGT-- TGG-AACGCT---TTGGTCC

I want to replace the leading and trailing, but not internal, -s of each line with ?s to get this result:
?????AACGCT--TTGGT?? ?GG-TAACGCT--TTGGT?? TGG-AACGCT---TTGGTCC

Finding the leading and trailing -s is an easy regexp ( ^[-]* and [-]*$ ), but is there an efficient way to replace them with the same number of ?s ?

Now I'm using a horrible and slow sed script to do that.

code:

sed 's/^-/\?/' myfile >leadingdeleter1
var0=0
while [ " $var0" -lt "$LIMIT" ]
do
        sed 's/\?-/\?\?/' leadingdeleter1 > leadingdeleter2
        sed 's/\?-/\?\?/' leadingdeleter2 > leadingdeleter1
let "var0 += 1"
done

I prefer to stay in shellscript, but if perl would be much more efficient, I'll try that.

# ¿ Mar 31, 2008 17:48

The Something Awful Forums > Discussion > Serious Hardware/Software Crap > The Cavern of COBOL > Ask General Programming Questions Not Worth Their Own Thread