I have file with a few lines:
x 1
y 2
z 3 t
I need to pass each line as paramater to some program:
$ program "x 1" "y 2" "z 3 t"
I know how to do it with two commands:
$ readarray -t a < file
$ program "${a[#]}"
How can i do it with one command? Something like that:
$ program ??? file ???
The (default) options of your readarray command indicate that your file items are separated by newlines.
So in order to achieve what you want in one command, you can take advantage of the special IFS variable to use word splitting w.r.t. newlines (see e.g. this doc) and call your program with a non-quoted command substitution:
IFS=$'\n'; program $(cat file)
As suggested by #CharlesDuffy:
you may want to disable globbing by running beforehand set -f, and if you want to keep these modifications local, you can enclose the whole in a subshell:
( set -f; IFS=$'\n'; program $(cat file) )
to avoid the performance penalty of the parens and of the /bin/cat process, you can write instead:
( set -f; IFS=$'\n'; exec program $(<file) )
where $(<file) is a Bash equivalent to to $(cat file) (faster as it doesn't require forking /bin/cat), and exec consumes the subshell created by the parens.
However, note that the exec trick won't work and should be removed if program is not a real program in the PATH (that is, you'll get exec: program: not found if program is just a function defined in your script).
Passing a set of params should be more organized :
In this example case I'm looking for a file containing chk_disk_issue=something etc.. so I set the values by reading a config file which I pass in as a param.
# -- read specific variables from the config file (if found) --
if [ -f "${file}" ] ;then
while IFS= read -r line ;do
if ! [[ $line = *"#"* ]]; then
var="$(echo $line | cut -d'=' -f1)"
case "$var" in
chk_disk_issue)
chk_disk_issue="$(echo $line | tr -d '[:space:]' | cut -d'=' -f2 | sed 's/[^0-9]*//g')"
;;
chk_mem_issue)
chk_mem_issue="$(echo $line | tr -d '[:space:]' | cut -d'=' -f2 | sed 's/[^0-9]*//g')"
;;
chk_cpu_issue)
chk_cpu_issue="$(echo $line | tr -d '[:space:]' | cut -d'=' -f2 | sed 's/[^0-9]*//g')"
;;
esac
fi
done < "${file}"
fi
if these are not params then find a way for your script to read them as data inside of the script and pass in the file name.
Here is my code
cd /bin/
echo *xyz?2* | cut -f 1 -d '.'
Please, how can i change this command to display files without extension ?
Bests.
Dump the filenames into an array and then use parameter expansion:
$ arr=(xyz?2*); echo "${arr[*]%.*}"
xyz32281 xyz32406 xyz32459 xyz3252 xyz7214 xyz8286
Assuming your filenames don't have any whitespace or glob characters.
You can just use printf '%s\n' instead of echo in your command:
printf '%s\n' *xyz?2* | cut -f 1 -d '.'
xyz32281
xyz32406
xyz32459
xyz3252
xyz7214
xyz8286
If you must use echo then use awk as this:
echo *xyz?2* | awk '{for(i=1; i<=NF; i++) print (split($i, a, /\./)==2 ? a[1] : $i)}'
xyz32281
xyz32406
xyz32459
xyz3252
xyz7214
xyz8286
This awk command iterated through each filename matched by glob pattern and splits each name by dot. If dot is found then first part is printed otherwise full filename is printed.
Your problem is that all files of echo *xyz?2* are shown in one line. When the filenames are without spaces/newlines, you can fix this by moving them to different lines and joining theem again when finished.
echo *xyz?2* | tr ' ' '\n' | cut -f 1 -d '.' | tr '\n' ' '| sed '$s/ $/\n/'
You can do this a lot easier with sed:
echo *xyz?2* | sed 's/[.][^. ]*//g'
I'm trying to run an application that needs a parameter passed in single or double quotes:
bwa mem -R '#RG\tID:foo\tLB=foo\tPL=illumina\tPU=1234.1\tSM=bar' ...
I'm trying to run this in a script:
#!/usr/bin/bash
var=foo_bar
first=$(echo $var | cut -d '_' -f 1)
second=$(echo $var | cut -d '_' -f 2)
readgroup="#RG\tID:$first\tLB=HUM\tPL=illumina\tPU=1234.1\tSM=$second"
echo \'$readgroup\'
'#RG\tID:foo\tLB=HUM\tPL=illumina\tPU=1234.1\tSM=bar'
However, when I use this as a parameter in my application call:
var=foo_bar
first=$(echo $var | cut -d '_' -f 1)
second=$(echo $var | cut -d '_' -f 2)
readgroup="#RG\tID:$first\tLB=HUM\tPL=illumina\tPU=1234.1\tSM=$second"
bwa mem -R \'$readgroup\' ...
it's interpreted as
\'#RG\tID:HUM-7\tLB=HUM\tPL=illumina\tPU=1234.1\tSM=HUM-7\'
What am I doing wrong?
The application doesn't care about the quotes; they are only used to protect the string from the shell.
var=foo_bar
IFS=_ read first second <<< "$var"
readgroup="#RG\tID:$first\tLB=HUM\tPL=illumina\tPU=1234.1\tSM=$second"
bwa mem -R "$readgroup"
If the \t are actually supposed to be literal tab characters, consider using printf instead of an assignment statement.
printf -v readgroup '#RG\tID:%s\tLB=HUM\tPL=illumina\tPU=1234.1\tSM=%s' "$first" "$second"
Should be like:
readgroup="'#RG\tID:$first\tLB=HUM\tPL=illumina\tPU=1234.1\tSM=$second'" [with '' wrapping]
readgroup="#RG\tID:$first\tLB=HUM\tPL=illumina\tPU=1234.1\tSM=$second" [without]
Important thing is to use -e option for echo [ See man echo ]
echo -e $readgroup
My code is:
nb_lignes=`wc -l $1 | cut -d " " -f1`
for i in $(seq $(($nb_lignes - 1)) )
do
machine=`head $1 -n $i | tail -1`
machine1=`head $1 -n $nb_lignes | tail -1`
ssh root#$machine -x " scp /home/file.txt root#$machine1:/home && rm -r /home/file.txt"
done
Is $machine1 taken as a variable or a string? If a string, how can I change it — by adding a quote?
$machine will expand to head $1 -n $i | tail -1 result, $machine1 will expand to head $1 -n $nb_lignes | tail -1 result.
You could figured it out by yourself.
Btw, ssh root# …
$machine1 will be expanded to give the value of variable machine1, because you are using double quotes". If you had used single quotes ' then it would not have been expanded.
One possible confusion is when you embed a variable inside other text. In this case you are fine, because the trailing character is a : (root#$machine1:/home) which is not a valid character in a Bash variable name. Some shells (csh) would not have liked that, if you are not sure then you can delimit the variable name using { }, for example:
root#${machine1}:/home
I want to uppercase just the first character in my string with bash.
foo="bar";
//uppercase first character
echo $foo;
should print "Bar";
One way with bash (version 4+):
foo=bar
echo "${foo^}"
prints:
Bar
foo="$(tr '[:lower:]' '[:upper:]' <<< ${foo:0:1})${foo:1}"
One way with sed:
echo "$(echo "$foo" | sed 's/.*/\u&/')"
Prints:
Bar
$ foo="bar";
$ foo=`echo ${foo:0:1} | tr '[a-z]' '[A-Z]'`${foo:1}
$ echo $foo
Bar
To capitalize first word only:
foo='one two three'
foo="${foo^}"
echo $foo
One two three
To capitalize every word in the variable:
foo="one two three"
foo=( $foo ) # without quotes
foo="${foo[#]^}"
echo $foo
One Two Three
(works in bash 4+)
Using awk only
foo="uNcapItalizedstrIng"
echo $foo | awk '{print toupper(substr($0,0,1))tolower(substr($0,2))}'
Here is the "native" text tools way:
#!/bin/bash
string="abcd"
first=`echo $string|cut -c1|tr [a-z] [A-Z]`
second=`echo $string|cut -c2-`
echo $first$second
just for fun here you are :
foo="bar";
echo $foo | awk '{$1=toupper(substr($1,0,1))substr($1,2)}1'
# or
echo ${foo^}
# or
echo $foo | head -c 1 | tr [a-z] [A-Z]; echo $foo | tail -c +2
# or
echo ${foo:1} | sed -e 's/^./\B&/'
It can be done in pure bash with bash-3.2 as well:
# First, get the first character.
fl=${foo:0:1}
# Safety check: it must be a letter :).
if [[ ${fl} == [a-z] ]]; then
# Now, obtain its octal value using printf (builtin).
ord=$(printf '%o' "'${fl}")
# Fun fact: [a-z] maps onto 0141..0172. [A-Z] is 0101..0132.
# We can use decimal '- 40' to get the expected result!
ord=$(( ord - 40 ))
# Finally, map the new value back to a character.
fl=$(printf '%b' '\'${ord})
fi
echo "${fl}${foo:1}"
This works too...
FooBar=baz
echo ${FooBar^^${FooBar:0:1}}
=> Baz
FooBar=baz
echo ${FooBar^^${FooBar:1:1}}
=> bAz
FooBar=baz
echo ${FooBar^^${FooBar:2:2}}
=> baZ
And so on.
Sources:
Bash Manual: Shell Parameter Expansion
Full Bash Guide: Parameters
Bash Hacker's Wiki Parameter Expansion
Inroductions/Tutorials:
Cyberciti.biz: 8. Convert to upper to lower case or vice versa
Opensource.com: An introduction to parameter expansion in Bash
This one worked for me:
Searching for all *php file in the current directory , and replace the first character of each filename to capital letter:
e.g: test.php => Test.php
for f in *php ; do mv "$f" "$(\sed 's/.*/\u&/' <<< "$f")" ; done
Alternative and clean solution for both Linux and OSX, it can also be used with bash variables
python -c "print(\"abc\".capitalize())"
returns Abc
This is POSIX sh-compatible as far as I know.
upper_first.sh:
#!/bin/sh
printf "$1" | cut -c1 -z | tr -d '\0' | tr [:lower:] [:upper:]
printf "$1" | cut -c2-
cut -c1 -z ends the first string with \0 instead of \n. It gets removed with tr -d '\0'. It also works to omit the -z and use tr -d '\n' instead, but this breaks if the first character of the string is a newline.
Usage:
$ upper_first.sh foo
Foo
$
In a function:
#!/bin/sh
function upper_first ()
{
printf "$1" | cut -c1 -z | tr -d '\0' | tr [:lower:] [:upper:]
printf "$1" | cut -c2-
}
old="foo"
new="$(upper_first "$old")"
echo "$new"
Posix compliant and with less sub-processes:
v="foo[Bar]"
printf "%s" "${v%"${v#?}"}" | tr '[:lower:]' '[:upper:]' && printf "%s" "${v#?}"
==> Foo[Bar]
first-letter-to-lower () {
str=""
space=" "
for i in $#
do
if [ -z $(echo $i | grep "the\|of\|with" ) ]
then
str=$str"$(echo ${i:0:1} | tr '[A-Z]' '[a-z]')${i:1}$space"
else
str=$str${i}$space
fi
done
echo $str
}
first-letter-to-upper-xc () {
v-first-letter-to-upper | xclip -selection clipboard
}
first-letter-to-upper () {
str=""
space=" "
for i in $#
do
if [ -z $(echo $i | grep "the\|of\|with" ) ]
then
str=$str"$(echo ${i:0:1} | tr '[a-z]' '[A-Z]')${i:1}$space"
else
str=$str${i}$space
fi
done
echo $str
}
first-letter-to-lower-xc(){
v-first-letter-to-lower | xclip -selection clipboard
}
Not exactly what asked but quite helpful
declare -u foo #When the variable is assigned a value, all lower-case characters are converted to upper-case.
foo=bar
echo $foo
BAR
And the opposite
declare -l foo #When the variable is assigned a value, all upper-case characters are converted to lower-case.
foo=BAR
echo $foo
bar
What if the first character is not a letter (but a tab, a space, and a escaped double quote)? We'd better test it until we find a letter! So:
S=' \"ó foo bar\"'
N=0
until [[ ${S:$N:1} =~ [[:alpha:]] ]]; do N=$[$N+1]; done
#F=`echo ${S:$N:1} | tr [:lower:] [:upper:]`
#F=`echo ${S:$N:1} | sed -E -e 's/./\u&/'` #other option
F=`echo ${S:$N:1}
F=`echo ${F} #pure Bash solution to "upper"
echo "$F"${S:(($N+1))} #without garbage
echo '='${S:0:(($N))}"$F"${S:(($N+1))}'=' #garbage preserved
Foo bar
= \"Foo bar=