Let's say I have a command my_command which I am sure outputs three lines like
line 1
line 2
line 3
and I want to store the three lines into three variables $x, $y, $z. How can I accomplish this in bash?
for name in x y z; do
read $name
done < <(my_command)
This uses process substitution so that the read commands are not executed in a subshell and the resulting variables are available after the loop completes. The variable name is used to hold the names of the variables to set; $name expands to the name of the variable that read sets, so after the loop you have three variables x, y, and z that hold each of the three lines of your output.
You can also use a here document instead of process substitution:
for name in x y z; do
read $name
done <<EOF
$(my_command)
EOF
And here's another:
IFS=$'\n' read -d '' x y z __ < <(my_command)
With -d '' it sets the delimiter to '\0' and makes read read the whole input in one instance, and not just a single line. IFS=$'\n' sets newline (\n) as the separator for each value. __ is optional and gathers any extra input besides the first 3 lines.
From help read:
Reads a single line from the standard input, or from file descriptor
FD if the -u option is supplied. The line is split into fields as with
word splitting, and the first word is assigned to the first NAME, the
second word to the second NAME, and so on, with any leftover words
assigned to the last NAME. Only the characters found in $IFS are
recognized as word delimiters.
-d delim continue until the first character of DELIM is read, rather than newline
Related
So I have a variable TRAILER which contains about 50 character. This variable is defined earlier in my shell session. As you can probably tell, it's a trailer to a file we'll be sending. I need to insert the record count of that file into the trailer. This record count is going to be 9 digits long (left padded with zeros if need be) and will start at index 2 of that string TRAILER. I want to retain all other characters in the TRAILER string just insert the RECORD_COUNT variable value into the TRAILER variable starting at index 2 (3rd character)
So the trailer variable is defined like this:
#Trailer details
TRAILER_RECORD_IDENTIFER="T"
LIFE_CYCLE="${LIFE_CYCLE_ENV}"
RECORD_COUNT="" #This will be calculated in the wrapper during the creation step
FILE_NUMBER="1111"
FILE_COUNT="1111"
CONTROL_TOTAL_1=" "
CONTROL_TOTAL_2=" "
CONTROL_TOTAL_3=" "
CONTROL_TOTAL_4=" "
CONTROL_TOTAL_5=" "
TRAILER="${TRAILER_RECORD_IDENTIFER}"\
"${LIFE_CYCLE}"\
"${RECORD_COUNT}"\
"${FILE_NUMBER}"\
"${FILE_COUNT}"\
"${CONTROL_TOTAL_1}"\
"${CONTROL_TOTAL_2}"\
"${CONTROL_TOTAL_3}"\
"${CONTROL_TOTAL_4}"\
"${CONTROL_TOTAL_5}"
Which then prints TRAILER as
TRAILER="TD11111111......" that would be 75 blank spaces for all of the white characters defined by the CONTROL_TOTAL variables.
These variables ALL get defined in the beginning of the shell. REcord count is defined but left blank ebcause we won't know the specific file until later int he shell.
Later in the shell i know the file that i want to use, i get the record coun:
cat ${ADE_DATA_FL_PATH_TMP} | wc -l | read ADE_DATA_FL_PATH_TMP_REC_COUNT >> ${LOG_FILE} 2>&1
Now I want to take ADE_DATA_FL_PATH_TMP_REC_COUNT and write that value into the TRAILER variable starting at the 2nd index, padded with zero's to be 9 characters long. So if my record count is 2700 records the new trailer would look like...
TRAILER="TD00000270011111111......"
You can use printf for padding.
I use TD as fixed first two characters, you can change this the way you want.
printf -v TRAILER "TD%.9d%s" "${ADE_DATA_FL_PATH_TMP_REC_COUNT}" "$(cut -c 12- <<< "${TRAILER}")"
Perhaps this is a good time switching to writing variable names in lowercase.
How can I print a command output like one from rm -rv * in a single line ? I think it would need \r but I can't figure out how.
I would need to have something like this :
From:
removed /path/file1
removed /path/file2
removed /path/file3
To : Line 1 : removed /path/file1
Then : Line 1 : removed /path/file2
Then : Line 1 : removed /path/file3
EDIT : I may have been misunderstood, I want to have the whole process beeing printing in a single same line, changing as the command outputs an another line (like removed /path/file123)
EDIT2 : The output is sometimes too long to be display in on line (very long path). I would need something that considers that problem too :
/very/very/very/long/path/to/a/very/very/very/far/file/with-a-very-very-very-long-name1
/very/very/very/long/path/to/a/very/very/very/far/file/with-a-very-very-very-long-name2
/very/very/very/long/path/to/a/very/very/very/far/file/with-a-very-very-very-long-name3
Here's a helper function:
shopt -s checkwinsize # ensure that COLUMNS is available w/ window size
oneline() {
local ws
while IFS= read -r line; do
if (( ${#line} >= COLUMNS )); then
# Moving cursor back to the front of the line so user input doesn't force wrapping
printf '\r%s\r' "${line:0:$COLUMNS}"
else
ws=$(( COLUMNS - ${#line} ))
# by writing each line twice, we move the cursor back to position
# thus: LF, content, whitespace, LF, content
printf '\r%s%*s\r%s' "$line" "$ws" " " "$line"
fi
done
echo
}
Used as follows:
rm -rv -- * 2>&1 | oneline
To test this a bit more safely, one might use:
for f in 'first line' 'second line' '3rd line'; do echo "$f"; sleep 1; done | oneline
...you'll see that that test displays first line for a second, then second line for a second, then 3rd line for a second.
If you want a "status line" result that is showing the last line output by the program where the line gets over-written by the next line when it comes out you can send the output for the command through a short shell while loop like this:
YourCommand | while read line ; do echo -n "$line"$' ...[lots of spaces]... \r' ; done
The [Lots of spaces] is needed in case a shorter line comes after a longer line. The short line needs to overwrite the text from the longer line or you will see residual characters from the long line.
The echo -n $' ... \r' sends a literal carriage return without a line-feed to the screen which moves the position back to the front of the line but doesn't move down a line.
If you want the text from your command to just be output in 1 long line, then
pipe the output of any command through this sed command and it should replace the carriage returns with spaces. This will put the output all on one line. You could change the space to another delimiter if desired.
your command | sed ':rep; {N;}; s/\n/ /; {t rep};'
:rep; is a non-command that marks where to go to in the {t rep} command.
{N;} will join the current line to the next line.
It doesn't remove the carriage return but just puts the 2 lines in the buffer to be used for following commands.
s/\n/ /; Says to replace the carriage return character with a space character. They space is between the second and third/ characters.
You may need to replace \r\n depending on if the file has line feeds. UNIX files don't unless they came from a pc and haven't been converted.
{t rep}; says that if the match was found in the s/// command then go to the :rep; marker.
This will keep joining lines, removing the \n, then jumping to :rep; until there are no more likes to join.
I have a variable equal to a string, which is a series of key/value pairs separated by newlines.
I want to then replace these newline characters with spaces, and set a new variable equal to the result
From various answers on the internet I've arrived at the following:
#test.txt has the content:
#test=example
#what=s0omething
vars="$(cat ./test.txt)"
formattedVars= $("$vars" | tr '\n' ' ')
echo "$taliskerEnvVars"
Problem is when I try to set formattedVars it tries to execute the second line:
script.sh: line 7: test=example
what=s0omething: command not found
I just want formattedVars to equal test=example what=s0omething
What trick am I missing?
Change your line to:
formattedVars=$(tr '\n' ' ' <<< "$secretsContent")
Notice the space of = in your code, which is not permitted in assignment statements.
I see that you are not setting secretsContent in your code, you are setting vars instead.
If possible, use an array to hold contents of the file:
readarray -t vars < ./test.txt # bash 4
or
# bash 3.x
declare -a vars
while IFS= read -r line; do
vars+=( "$line" )
done < ./test.txt
Then you can do what you need with the array. You can make your space-separated list with
formattedVars="${vars[*]}"
, but consider whether you need to. If the goal is to use them as a pre-command modifier, use, for instance,
"${vars[#]}" my_command arg1 arg2
The below loop should read 1 line at a time to the veriable m. But it prints some junk value. Please help.
MyMachine:/u/home/Mohammed_Junaid> cat /tmp/F5
[10.222.73.99:22]
[10.000.73.99:22]
[10.111.73.99:22]
MyMachine:/u/home/Mohammed_Junaid>
MyMachine:/u/home/Mohammed_Junaid> for m in $(cat /tmp/F5); do echo $m;done
1
2
1
2
1
2
MyMachine:/u/home/Mohammed_Junaid>
Those strings are also valid glob-patterns. Because you're not quoting the $m variable, you're letting the shell perform filename expansion.
It happens that the string [10.222.73.99:22] is equivalent to the glob pattern [012739.:] which will match a filename of a single one of those characters, and it appears that you have a file named 1 and a file named 2 in your current directory.
Always quote your shell variables, and don't use for to iterate the lines of a file
while IFS= read -r m; do echo "$m"; done < /tmp/F5
I wrote 2 difference scripts but I am stuck at the same problem.
The problem is am making a table from a file ($2) that I get in args and $1 is the numbers of columns. A little bit hard to explain but I am gonna show you input and output.
The problem is now that I don't know how I can save every column now in a difference var so i can build it in my HTML code later
#printf #TR##TD#$...#/TD##TD#$...#/TD##TD#$..#/TD##/TR##TD#$...
so input look like that :
Name\tSize\tType\tprobe
bla\t4711\tfile\t888888888
abcde\t4096\tdirectory\t5555
eeeee\t333333\tblock\t6666
aaaaaa\t111111\tpackage\t7777
sssss\t44444\tfile\t8888
bbbbb\t22222\tfolder\t9999
Code :
c=1
column=$1
file=$2
echo "$( < $file)"| while read Line ; do
Name=$(sed "s/\\\t/ /g" $file | cut -d' ' -f$c,-$column)
printf "$Name \n"
#let c=c+1
#printf "<TR><TD>$Name</TD><TD>$Size</TD><TD>$Type</TD></TR>\n"
exit 0
done
Output:
Name Size Type probe
bla 4711 file 888888888
abcde 4096 directory 5555
eeeee 333333 block 6666
aaaaaa 111111 package 7777
sssss 44444 file 8888
bbbbb 22222 folder 9999
This is tailor-made job for awk. See this script:
awk -F'\t' '{printf "<tr>";for(i=1;i<=NF;i++) printf "<td>%s</td>", $i;print "</tr>"}' input
<tr><td>bla</td><td>4711</td><td>file</td><td>888888888</td></tr>
<tr><td>abcde</td><td>4096</td><td>directory</td><td>5555</td></tr>
<tr><td>eeeee</td><td>333333</td><td>block</td><td>6666</td></tr>
<tr><td>aaaaaa</td><td>111111</td><td>package</td><td>7777</td></tr>
<tr><td>sssss</td><td>44444</td><td>file</td><td>8888</td></tr>
<tr><td>bbbbb</td><td>22222</td><td>folder</td><td>9999</td></tr>
In bash:
celltype=th
while IFS=$'\t' read -a columns; do
rowcontents=$( printf '<%s>%s</%s>' "$celltype" "${columns[#]}" "$celltype" )
printf '<tr>%s</tr>\n' "$rowcontents"
celltype=td
done < <( sed $'s/\\\\t/\t/g' "$2")
Some explanations:
IFS=$'\t' read -a columns reads a line from standard input, using only the tab character to separate fields, and putting each field into a separate element of the array columns. We change IFS so that other whitespace, which could occur in a field, is not treated as a field delimiter.
On the first line read from standard input, <th> elements will be output by the printf line. After resetting the value of celltype at the end of the loop body, all subsequent rows will consist of <td> elements.
When setting the value of rowcontents, take advantage of the fact that the first argument is repeated as many times as necessary to consume all the arguments.
Input is via process substitution from the sed command, which requires a crazy amount of quoting. First, the entire argument is quoted with $'...', which tells bash to replace escaped characters. bash converts this to the literal string s/\\t/^T/g, where I am using ^T to represent a literal ASCII 09 tab character. When sed sees this argument, it performs its own escape replacement, so the search text is a literal backslash followed by a literal t, to be replaced by a literal tab character.
The first argument, the column count, is unnecessary and is ignored.
Normally, you avoid making the while loop part of a pipeline because you set parameters in the loop that you want to use later. Here, all the variables are truly local to the while loop, so you could avoid the process substitution and use a pipeline if you wish:
sed $'s/\\\\t/\t/g' "$2" | while IFS=$'\t' read -a columns; do
...
done