I have file abc.sh which contains below data -
a_a_1 was unsuccessful
a_a_5 was completed
a_a_2 was unsuccessful
a_a_4 was unsuccessful
a_a_9 was unsuccessful
now, I have a variable abc which contains value 2,1,9 ..i.e abc=2,1,9
now want to print only those lines from file which matches value 2,1,9 and above string.
output should be like-
a_a_2 was unsuccessful
a_a_1 was unsuccessful
a_a_9 was unsuccessful
How to achieve above output?
Since this is tagged tcl...
#!/usr/bin/env tclsh
proc main {abc} {
set abc [string map {, |} $abc]
set re [string cat {^a_a_(?:} $abc {)\M}]
while {[gets stdin line] >= 0} {
if {[regexp $re $line]} {
puts $line
}
}
}
main [lindex $argv 0]
Example usage:
$ ./findit.tcl 2,1,9 < abc.sh
Basically, it converts the CSV 2,1,9 into pipe delimited 2|1|9 and uses that as part of a bigger regular expression, and prints lines read from standard input that match it.
Since you also seem to be interested in a bash solution (you already got one for Tcl):
grep -E "_(${abc//,/|}) " abc.sh
The idea here is to translate the 2,1,9 into the regexp pattern 2|1|9. An alternative, similar in spirit, would be
grep "_[${abc//,/}] " abc.sh
which produces the pattern [219].
Your variable need to be:
abc="2\|1\|9" for grep $abc abc.sh
a=2 b=1 c=9 for grep "[$a]\|[$b]\|[$c]" abc.sh
Well as your question, if you want for abc=2,1,9 , you can just change the , as \| using sed when executing grep like this:
grep $(echo $abc | sed "s/,/\\\|/g") abc.sh
*ps: English is not my primary language so please excuse any grammar mistakes :)
Related
I have two strings saved in a bash variable delimited by :. I want to get extract the second string, prepend that with THIS_VAR= and append it to a file named saved.txt
For example if myVar="abc:pqr", THIS_VAR=pqr should be appended to saved.txt.
This is what I have so far,
myVar="abc:pqr"
echo $myVar | cut -d ':' -f 2 >> saved.txt
How do I prepend THIS_VAR=?
printf 'THIS_VAR=%q\n' "${myVar#*:}"
See Shell Parameter Expansion and run help printf.
The more general solution in addition to #konsolebox's answer is piping into a compound statement, where you can perform arbitrary operations:
echo This is in the middle | {
echo This is first
cat
echo This is last
}
In my bash script I have an external (received from user) string, which I should use in sed pattern.
REPLACE="<funny characters here>"
sed "s/KEYWORD/$REPLACE/g"
How can I escape the $REPLACE string so it would be safely accepted by sed as a literal replacement?
NOTE: The KEYWORD is a dumb substring with no matches etc. It is not supplied by user.
Warning: This does not consider newlines. For a more in-depth answer, see this SO-question instead. (Thanks, Ed Morton & Niklas Peter)
Note that escaping everything is a bad idea. Sed needs many characters to be escaped to get their special meaning. For example, if you escape a digit in the replacement string, it will turn in to a backreference.
As Ben Blank said, there are only three characters that need to be escaped in the replacement string (escapes themselves, forward slash for end of statement and & for replace all):
ESCAPED_REPLACE=$(printf '%s\n' "$REPLACE" | sed -e 's/[\/&]/\\&/g')
# Now you can use ESCAPED_REPLACE in the original sed statement
sed "s/KEYWORD/$ESCAPED_REPLACE/g"
If you ever need to escape the KEYWORD string, the following is the one you need:
sed -e 's/[]\/$*.^[]/\\&/g'
And can be used by:
KEYWORD="The Keyword You Need";
ESCAPED_KEYWORD=$(printf '%s\n' "$KEYWORD" | sed -e 's/[]\/$*.^[]/\\&/g');
# Now you can use it inside the original sed statement to replace text
sed "s/$ESCAPED_KEYWORD/$ESCAPED_REPLACE/g"
Remember, if you use a character other than / as delimiter, you need replace the slash in the expressions above wih the character you are using. See PeterJCLaw's comment for explanation.
Edited: Due to some corner cases previously not accounted for, the commands above have changed several times. Check the edit history for details.
The sed command allows you to use other characters instead of / as separator:
sed 's#"http://www\.fubar\.com"#URL_FUBAR#g'
The double quotes are not a problem.
The only three literal characters which are treated specially in the replace clause are / (to close the clause), \ (to escape characters, backreference, &c.), and & (to include the match in the replacement). Therefore, all you need to do is escape those three characters:
sed "s/KEYWORD/$(echo $REPLACE | sed -e 's/\\/\\\\/g; s/\//\\\//g; s/&/\\\&/g')/g"
Example:
$ export REPLACE="'\"|\\/><&!"
$ echo fooKEYWORDbar | sed "s/KEYWORD/$(echo $REPLACE | sed -e 's/\\/\\\\/g; s/\//\\\//g; s/&/\\\&/g')/g"
foo'"|\/><&!bar
Based on Pianosaurus's regular expressions, I made a bash function that escapes both keyword and replacement.
function sedeasy {
sed -i "s/$(echo $1 | sed -e 's/\([[\/.*]\|\]\)/\\&/g')/$(echo $2 | sed -e 's/[\/&]/\\&/g')/g" $3
}
Here's how you use it:
sedeasy "include /etc/nginx/conf.d/*" "include /apps/*/conf/nginx.conf" /etc/nginx/nginx.conf
It's a bit late to respond... but there IS a much simpler way to do this. Just change the delimiter (i.e., the character that separates fields). So, instead of s/foo/bar/ you write s|bar|foo.
And, here's the easy way to do this:
sed 's|/\*!50017 DEFINER=`snafu`#`localhost`\*/||g'
The resulting output is devoid of that nasty DEFINER clause.
It turns out you're asking the wrong question. I also asked the wrong question. The reason it's wrong is the beginning of the first sentence: "In my bash script...".
I had the same question & made the same mistake. If you're using bash, you don't need to use sed to do string replacements (and it's much cleaner to use the replace feature built into bash).
Instead of something like, for example:
function escape-all-funny-characters() { UNKNOWN_CODE_THAT_ANSWERS_THE_QUESTION_YOU_ASKED; }
INPUT='some long string with KEYWORD that need replacing KEYWORD.'
A="$(escape-all-funny-characters 'KEYWORD')"
B="$(escape-all-funny-characters '<funny characters here>')"
OUTPUT="$(sed "s/$A/$B/g" <<<"$INPUT")"
you can use bash features exclusively:
INPUT='some long string with KEYWORD that need replacing KEYWORD.'
A='KEYWORD'
B='<funny characters here>'
OUTPUT="${INPUT//"$A"/"$B"}"
Use awk - it is cleaner:
$ awk -v R='//addr:\\file' '{ sub("THIS", R, $0); print $0 }' <<< "http://file:\_THIS_/path/to/a/file\\is\\\a\\ nightmare"
http://file:\_//addr:\file_/path/to/a/file\\is\\\a\\ nightmare
Here is an example of an AWK I used a while ago. It is an AWK that prints new AWKS. AWK and SED being similar it may be a good template.
ls | awk '{ print "awk " "'"'"'" " {print $1,$2,$3} " "'"'"'" " " $1 ".old_ext > " $1 ".new_ext" }' > for_the_birds
It looks excessive, but somehow that combination of quotes works to keep the ' printed as literals. Then if I remember correctly the vaiables are just surrounded with quotes like this: "$1". Try it, let me know how it works with SED.
These are the escape codes that I've found:
* = \x2a
( = \x28
) = \x29
" = \x22
/ = \x2f
\ = \x5c
' = \x27
? = \x3f
% = \x25
^ = \x5e
sed is typically a mess, especially the difference between gnu-sed and bsd-sed
might just be easier to place some sort of sentinel at the sed side, then a quick pipe over to awk, which is far more flexible in accepting any ERE regex, escaped hex, or escaped octals.
e.g. OFS in awk is the true replacement ::
date | sed -E 's/[0-9]+/\xC1\xC0/g' |
mawk NF=NF FS='\xC1\xC0' OFS='\360\237\244\241'
1 Tue Aug 🤡 🤡:🤡:🤡 EDT 🤡
(tested and confirmed working on both BSD-sed and GNU-sed - the emoji isn't a typo that's what those 4 bytes map to in UTF-8 )
There are dozens of answers out there... If you don't mind using a bash function schema, below is a good answer. The objective below was to allow using sed with practically any parameter as a KEYWORD (F_PS_TARGET) or as a REPLACE (F_PS_REPLACE). We tested it in many scenarios and it seems to be pretty safe. The implementation below supports tabs, line breaks and sigle quotes for both KEYWORD and replace REPLACE.
NOTES: The idea here is to use sed to escape entries for another sed command.
CODE
F_REVERSE_STRING_R=""
f_reverse_string() {
: 'Do a string reverse.
To undo just use a reversed string as STRING_INPUT.
Args:
STRING_INPUT (str): String input.
Returns:
F_REVERSE_STRING_R (str): The modified string.
'
local STRING_INPUT=$1
F_REVERSE_STRING_R=$(echo "x${STRING_INPUT}x" | tac | rev)
F_REVERSE_STRING_R=${F_REVERSE_STRING_R%?}
F_REVERSE_STRING_R=${F_REVERSE_STRING_R#?}
}
# [Ref(s).: https://stackoverflow.com/a/2705678/3223785 ]
F_POWER_SED_ECP_R=""
f_power_sed_ecp() {
: 'Escape strings for the "sed" command.
Escaped characters will be processed as is (e.g. /n, /t ...).
Args:
F_PSE_VAL_TO_ECP (str): Value to be escaped.
F_PSE_ECP_TYPE (int): 0 - For the TARGET value; 1 - For the REPLACE value.
Returns:
F_POWER_SED_ECP_R (str): Escaped value.
'
local F_PSE_VAL_TO_ECP=$1
local F_PSE_ECP_TYPE=$2
# NOTE: Operational characters of "sed" will be escaped, as well as single quotes.
# By Questor
if [ ${F_PSE_ECP_TYPE} -eq 0 ] ; then
# NOTE: For the TARGET value. By Questor
F_POWER_SED_ECP_R=$(echo "x${F_PSE_VAL_TO_ECP}x" | sed 's/[]\/$*.^[]/\\&/g' | sed "s/'/\\\x27/g" | sed ':a;N;$!ba;s/\n/\\n/g')
else
# NOTE: For the REPLACE value. By Questor
F_POWER_SED_ECP_R=$(echo "x${F_PSE_VAL_TO_ECP}x" | sed 's/[\/&]/\\&/g' | sed "s/'/\\\x27/g" | sed ':a;N;$!ba;s/\n/\\n/g')
fi
F_POWER_SED_ECP_R=${F_POWER_SED_ECP_R%?}
F_POWER_SED_ECP_R=${F_POWER_SED_ECP_R#?}
}
# [Ref(s).: https://stackoverflow.com/a/24134488/3223785 ,
# https://stackoverflow.com/a/21740695/3223785 ,
# https://unix.stackexchange.com/a/655558/61742 ,
# https://stackoverflow.com/a/11461628/3223785 ,
# https://stackoverflow.com/a/45151986/3223785 ,
# https://linuxaria.com/pills/tac-and-rev-to-see-files-in-reverse-order ,
# https://unix.stackexchange.com/a/631355/61742 ]
F_POWER_SED_R=""
f_power_sed() {
: 'Facilitate the use of the "sed" command. Replaces in files and strings.
Args:
F_PS_TARGET (str): Value to be replaced by the value of F_PS_REPLACE.
F_PS_REPLACE (str): Value that will replace F_PS_TARGET.
F_PS_FILE (Optional[str]): File in which the replacement will be made.
F_PS_SOURCE (Optional[str]): String to be manipulated in case "F_PS_FILE" was
not informed.
F_PS_NTH_OCCUR (Optional[int]): [1~n] - Replace the nth match; [n~-1] - Replace
the last nth match; 0 - Replace every match; Default 1.
Returns:
F_POWER_SED_R (str): Return the result if "F_PS_FILE" is not informed.
'
local F_PS_TARGET=$1
local F_PS_REPLACE=$2
local F_PS_FILE=$3
local F_PS_SOURCE=$4
local F_PS_NTH_OCCUR=$5
if [ -z "$F_PS_NTH_OCCUR" ] ; then
F_PS_NTH_OCCUR=1
fi
local F_PS_REVERSE_MODE=0
if [ ${F_PS_NTH_OCCUR} -lt -1 ] ; then
F_PS_REVERSE_MODE=1
f_reverse_string "$F_PS_TARGET"
F_PS_TARGET="$F_REVERSE_STRING_R"
f_reverse_string "$F_PS_REPLACE"
F_PS_REPLACE="$F_REVERSE_STRING_R"
f_reverse_string "$F_PS_SOURCE"
F_PS_SOURCE="$F_REVERSE_STRING_R"
F_PS_NTH_OCCUR=$((-F_PS_NTH_OCCUR))
fi
f_power_sed_ecp "$F_PS_TARGET" 0
F_PS_TARGET=$F_POWER_SED_ECP_R
f_power_sed_ecp "$F_PS_REPLACE" 1
F_PS_REPLACE=$F_POWER_SED_ECP_R
local F_PS_SED_RPL=""
if [ ${F_PS_NTH_OCCUR} -eq -1 ] ; then
# NOTE: We kept this option because it performs better when we only need to replace
# the last occurrence. By Questor
# [Ref(s).: https://linuxhint.com/use-sed-replace-last-occurrence/ ,
# https://unix.stackexchange.com/a/713866/61742 ]
F_PS_SED_RPL="'s/\(.*\)$F_PS_TARGET/\1$F_PS_REPLACE/'"
elif [ ${F_PS_NTH_OCCUR} -gt 0 ] ; then
# [Ref(s).: https://unix.stackexchange.com/a/587924/61742 ]
F_PS_SED_RPL="'s/$F_PS_TARGET/$F_PS_REPLACE/$F_PS_NTH_OCCUR'"
elif [ ${F_PS_NTH_OCCUR} -eq 0 ] ; then
F_PS_SED_RPL="'s/$F_PS_TARGET/$F_PS_REPLACE/g'"
fi
# NOTE: As the "sed" commands below always process literal values for the "F_PS_TARGET"
# so we use the "-z" flag in case it has multiple lines. By Quaestor
# [Ref(s).: https://unix.stackexchange.com/a/525524/61742 ]
if [ -z "$F_PS_FILE" ] ; then
F_POWER_SED_R=$(echo "x${F_PS_SOURCE}x" | eval "sed -z $F_PS_SED_RPL")
F_POWER_SED_R=${F_POWER_SED_R%?}
F_POWER_SED_R=${F_POWER_SED_R#?}
if [ ${F_PS_REVERSE_MODE} -eq 1 ] ; then
f_reverse_string "$F_POWER_SED_R"
F_POWER_SED_R="$F_REVERSE_STRING_R"
fi
else
if [ ${F_PS_REVERSE_MODE} -eq 0 ] ; then
eval "sed -i -z $F_PS_SED_RPL \"$F_PS_FILE\""
else
tac "$F_PS_FILE" | rev | eval "sed -z $F_PS_SED_RPL" | tac | rev > "$F_PS_FILE"
fi
fi
}
MODEL
f_power_sed "F_PS_TARGET" "F_PS_REPLACE" "" "F_PS_SOURCE"
echo "$F_POWER_SED_R"
EXAMPLE
f_power_sed "{ gsub(/,[ ]+|$/,\"\0\"); print }' ./ and eliminate" "[ ]+|$/,\"\0\"" "" "Great answer (+1). If you change your awk to awk '{ gsub(/,[ ]+|$/,\"\0\"); print }' ./ and eliminate that concatenation of the final \", \" then you don't have to go through the gymnastics on eliminating the final record. So: readarray -td '' a < <(awk '{ gsub(/,[ ]+/,\"\0\"); print; }' <<<\"$string\") on Bash that supports readarray. Note your method is Bash 4.4+ I think because of the -d in readar"
echo "$F_POWER_SED_R"
IF YOU JUST WANT TO ESCAPE THE PARAMETERS TO THE SED COMMAND
MODEL
# "TARGET" value.
f_power_sed_ecp "F_PSE_VAL_TO_ECP" 0
echo "$F_POWER_SED_ECP_R"
# "REPLACE" value.
f_power_sed_ecp "F_PSE_VAL_TO_ECP" 1
echo "$F_POWER_SED_ECP_R"
IMPORTANT: If the strings for KEYWORD and/or replace REPLACE contain tabs or line breaks you will need to use the "-z" flag in your "sed" command. More details here.
EXAMPLE
f_power_sed_ecp "{ gsub(/,[ ]+|$/,\"\0\"); print }' ./ and eliminate" 0
echo "$F_POWER_SED_ECP_R"
f_power_sed_ecp "[ ]+|$/,\"\0\"" 1
echo "$F_POWER_SED_ECP_R"
NOTE: The f_power_sed_ecp and f_power_sed functions above was made available completely free as part of this project ez_i - Create shell script installers easily!.
Standard recommendation here: use perl :)
echo KEYWORD > /tmp/test
REPLACE="<funny characters here>"
perl -pi.bck -e "s/KEYWORD/${REPLACE}/g" /tmp/test
cat /tmp/test
don't forget all the pleasure that occur with the shell limitation around " and '
so (in ksh)
Var=">New version of \"content' here <"
printf "%s" "${Var}" | sed "s/[&\/\\\\*\\"']/\\&/g' | read -r EscVar
echo "Here is your \"text\" to change" | sed "s/text/${EscVar}/g"
If the case happens to be that you are generating a random password to pass to sed replace pattern, then you choose to be careful about which set of characters in the random string. If you choose a password made by encoding a value as base64, then there is is only character that is both possible in base64 and is also a special character in sed replace pattern. That character is "/", and is easily removed from the password you are generating:
# password 32 characters log, minus any copies of the "/" character.
pass=`openssl rand -base64 32 | sed -e 's/\///g'`;
If you are just looking to replace Variable value in sed command then just remove
Example:
sed -i 's/dev-/dev-$ENV/g' test to sed -i s/dev-/dev-$ENV/g test
I have an improvement over the sedeasy function, which WILL break with special characters like tab.
function sedeasy_improved {
sed -i "s/$(
echo "$1" | sed -e 's/\([[\/.*]\|\]\)/\\&/g'
| sed -e 's:\t:\\t:g'
)/$(
echo "$2" | sed -e 's/[\/&]/\\&/g'
| sed -e 's:\t:\\t:g'
)/g" "$3"
}
So, whats different? $1 and $2 wrapped in quotes to avoid shell expansions and preserve tabs or double spaces.
Additional piping | sed -e 's:\t:\\t:g' (I like : as token) which transforms a tab in \t.
An easier way to do this is simply building the string before hand and using it as a parameter for sed
rpstring="s/KEYWORD/$REPLACE/g"
sed -i $rpstring test.txt
I have the following string:
test1234a or test1234 for example and I want to extract only test from that string.
I tried the follwing
echo "Test12h" | sed -e 's/[0-9]\*$//' but is not working.
Is there any possibility to extract the substring until first digit?
Please let me know what I miss.
Thank you
The proper tool for extracting substrings matching a regexp from a command's output is grep. Like,
echo "Test12h" | grep -o '^[^[:digit:]]*'
will output Test.
If Test12h is in a variable, you don't even need external utilities; parameter expansions can easily handle that, e.g:
var='Test12h'
echo "${var%%[[:digit:]]*}"
Could you please try following.
sed 's/\([^0-9]*\).*/\1/' Input_file
OR
sed 's/[0-9][0-9a-zA-Z]*//' Input_file
If the source happens to reside in a variable you can use parameter substitution, eg:
$ for test in test1234a test1234 Test12h
do
echo "${test} => ${test//[0-9]*/}"
done
test1234a => test
test1234 => test
Test12h => Test
Where the general format is: ${var//Pattern/Replacement}; in the above:
var == test
Pattern == [0-9]* (first occurrence of a digit and then everything that follows
Replacement == '' (nothing, empty string)
So we end up stripping off everything after the first occurrence of a number.
You made a small error in your try:
echo "Test12h" | sed -e 's/[0-9].*$//' # will output Test
The \* expects a real * in the input:
echo "Test1*" | sed -e 's/[0-9]\*$//' # will output Test
The .* matches any number of any characters.
I'm trying to convert a string that has either - (hyphen) or _ (underscore) to Capital_Case string.
#!/usr/bin/env sh
function cap_case() {
[ $# -eq 1 ] || return 1;
_str=$1;
_capitalize=${_str//[-_]/_} | sed -E 's/(^|_)([a-zA-Z])/\u\2/g'
echo "Capitalize:"
echo $_capitalize
return 0
}
read string
echo $(cap_case $string)
But I don't get anything out.
First I am replacing any occurrence of - and _ with _ ${_str//[-_]/_}, and then I pipe that string to sed which finds the first letter, or _ as the first group, and then the letter after the first group in the second group, and I want to uppercase the found letter with \u\2. I tried with \U\2 but that didn't work as well.
I want the string some_string to become
Some_String
And string some-string to become
Some_String
I'm on a mac, using zsh if that is helpful.
EDIT: More generic solution here to make each field's first letter Capital.
echo "some_string_other" | awk -F"_" '{for(i=1;i<=NF;i++){$i=toupper(substr($i,1,1)) substr($i,2)}} 1' OFS="_"
Following awk may help you.
echo "some_string" | awk -F"_" '{$1=toupper(substr($1,1,1)) substr($1,2);$2=toupper(substr($2,1,1)) substr($2,2)} 1' OFS="_"
Output will be as follows.
echo "some_string" | awk -F"_" '{$1=toupper(substr($1,1,1)) substr($1,2);$2=toupper(substr($2,1,1)) substr($2,2)} 1' OFS="_"
Some_String
This being zsh, you don't need sed (or even a function, really):
$ s=some-string-bar
$ print ${(C)s:gs/-/_}
Some_String_Bar
The (C) flag capitalizes words (where "words" are defined as sequences of alphanumeric characters separated by other characters); :gs/-/_ replaces hyphens with underscores.
If you really want a function, it's cap_case () { print ${(C)1:gs/-/_} }.
pure bash:
#!/bin/bash
camel_case(){
local d display string
declare -a strings # = scope local
[ "$2" ] && d="$2" || d=" " # optional output delimiter
ifs_ini="$IFS"
IFS+='_-' # we keep initial IFS
strings=( "$1" ) # array
for string in ${strings[#]} ; do
display+="${string^}$d"
done
echo "${display%$d}"
IFS="$ifs_ini"
}
camel_case "some-string_here" "_"
camel_case "some-string_here some strings here" "+"
camel_case "some-string_here some strings here"
echo "$BASH_VERSION"
exit
output:
Some_String_Here
Some+String+Here+Some+Strings+Here
Some String Here Some Strings Here
4.4.18(1) release
You can try this gnu sed
echo 'some_other-string' | sed -E 's/(^.)/\u&/;s/[_-](.)/_\u\1/g'
Explains :
s/(^.)/\u&/
(^.) match the first char and \u& put the match in capital letter.
s/[_-](.)/_\u\1/g
[_-](.) capture a char preceded by _ or - and replace it by _ and the matched char in capital letter.
The g at the end tell sed to make the replacement for each char which meet the criteria
You didn't assign to _capitalize - you set a _capitalize environment variable for the empty command that you piped into sed.
You probably meant
_capitalize=$(<<<"${_str//[-_]/_}" sed -E 's/(^|_)([a-zA-Z])/\1\u\2/g')
Note also that ${//} isn't standard shell, so you really ought to specify an interpreter other than sh.
A simpler approach would be simply:
#!/bin/sh
cap_case() {
printf "Capitalize: "
echo "$*" | sed -e 'y/-/_/' -e 's/\(^\|_\)[[:alpha:]]/\U&/g'
}
echo $(cap_case "snake_case")
Note that the \u / \U replacement is a GNU extension to sed - if you're using a non-GNU implementation, check whether it supports this feature.
How to I concatenate stdin to a string, like this?
echo "input" | COMMAND "string"
and get
inputstring
A bit hacky, but this might be the shortest way to do what you asked in the question (use a pipe to accept stdout from echo "input" as stdin to another process / command:
echo "input" | awk '{print $1"string"}'
Output:
inputstring
What task are you exactly trying to accomplish? More context can get you more direction on a better solution.
Update - responding to comment:
#NoamRoss
The more idiomatic way of doing what you want is then:
echo 'http://dx.doi.org/'"$(pbpaste)"
The $(...) syntax is called command substitution. In short, it executes the commands enclosed in a new subshell, and substitutes the its stdout output to where the $(...) was invoked in the parent shell. So you would get, in effect:
echo 'http://dx.doi.org/'"rsif.2012.0125"
use cat - to read from stdin, and put it in $() to throw away the trailing newline
echo input | COMMAND "$(cat -)string"
However why don't you drop the pipe and grab the output of the left side in a command substitution:
COMMAND "$(echo input)string"
I'm often using pipes, so this tends to be an easy way to prefix and suffix stdin:
echo -n "my standard in" | cat <(echo -n "prefix... ") - <(echo " ...suffix")
prefix... my standard in ...suffix
There are some ways of accomplish this, i personally think the best is:
echo input | while read line; do echo $line string; done
Another can be by substituting "$" (end of line character) with "string" in a sed command:
echo input | sed "s/$/ string/g"
Why i prefer the former? Because it concatenates a string to stdin instantly, for example with the following command:
(echo input_one ;sleep 5; echo input_two ) | while read line; do echo $line string; done
you get immediatly the first output:
input_one string
and then after 5 seconds you get the other echo:
input_two string
On the other hand using "sed" first it performs all the content of the parenthesis and then it gives it to "sed", so the command
(echo input_one ;sleep 5; echo input_two ) | sed "s/$/ string/g"
will output both the lines
input_one string
input_two string
after 5 seconds.
This can be very useful in cases you are performing calls to functions which takes a long time to complete and want to be continuously updated about the output of the function.
You can do it with sed:
seq 5 | sed '$a\6'
seq 5 | sed '$ s/.*/\0 6/'
In your example:
echo input | sed 's/.*/\0string/'
I know this is a few years late, but you can accomplish this with the xargs -J option:
echo "input" | xargs -J "%" echo "%" "string"
And since it is xargs, you can do this on multiple lines of a file at once. If the file 'names' has three lines, like:
Adam
Bob
Charlie
You could do:
cat names | xargs -n 1 -J "%" echo "I like" "%" "because he is nice"
Also works:
seq -w 0 100 | xargs -I {} echo "string "{}
Will generate strings like:
string 000
string 001
string 002
string 003
string 004
...
The command you posted would take the string "input" use it as COMMAND's stdin stream, which would not produce the results you are looking for unless COMMAND first printed out the contents of its stdin and then printed out its command line arguments.
It seems like what you want to do is more close to command substitution.
http://www.gnu.org/software/bash/manual/html_node/Command-Substitution.html#Command-Substitution
With command substitution you can have a commandline like this:
echo input `COMMAND "string"`
This will first evaluate COMMAND with "string" as input, and then expand the results of that commands execution onto a line, replacing what's between the ‘`’ characters.
cat will be my choice: ls | cat - <(echo new line)
With perl
echo "input" | perl -ne 'print "prefix $_"'
Output:
prefix input
A solution using sd (basically a modern sed; much easier to use IMO):
# replace '$' (end of string marker) with 'Ipsum'
# the `e` flag disables multi-line matching (treats all lines as one)
$ echo "Lorem" | sd --flags e '$' 'Ipsum'
Lorem
Ipsum#no new line here
You might observe that Ipsum appears on a new line, and the output is missing a \n. The reason is echo's output ends in a \n, and you didn't tell sd to add a new \n. sd is technically correct because it's doing exactly what you are asking it to do and nothing else.
However this may not be what you want, so instead you can do this:
# replace '\n$' (new line, immediately followed by end of string) by 'Ipsum\n'
# don't forget to re-add the `\n` that you removed (if you want it)
$ echo "Lorem" | sd --flags e '\n$' 'Ipsum\n'
LoremIpsum
If you have a multi-line string, but you want to append to the end of each individual line:
$ ls
foo bar baz
$ ls | sd '\n' '/file\n'
bar/file
baz/file
foo/file
I want to prepend my sql script with "set" statement before running it.
So I echo the "set" instruction, then pipe it to cat. Command cat takes two parameters : STDIN marked as "-" and my sql file, cat joins both of them to one output. Next I pass the result to mysql command to run it as a script.
echo "set #ZERO_PRODUCTS_DISPLAY='$ZERO_PRODUCTS_DISPLAY';" | cat - sql/test_parameter.sql | mysql
p.s. mysql login and password stored in .my.cnf file