echo [string] | sed "s/[original]/[target]/g"
For Dash all previous posts aren't working
The POSIX sh
compatible solution is:
result=$(echo "$firstString" | sed "s/Suzi/$secondString/")
This will replace the first occurrence on each line of input. Add a /g
flag to replace all occurrences:
result=$(echo "$firstString" | sed "s/Suzi/$secondString/g")
Pure POSIX shell method, which unlike Roman Kazanovskyi's sed
-based answer needs no external tools, just the shell's own native parameter expansions. Note that long file names are minimized so the code fits better on one line:
f="I love Suzi and Marry"
s=Sara
t=Suzi
[ "${f%$t*}" != "$f" ] && f="${f%$t*}$s${f#*$t}"
echo "$f"
Output:
I love Sara and Marry
How it works:
Remove Smallest Suffix Pattern. "${f%$t*}"
returns "I love
" if the suffix $t
"Suzi*
" is in $f
"I love
Suzi and Marry
".
But if t=Zelda
, then "${f%$t*}"
deletes nothing, and returns the whole string "I love Suzi and Marry
".
This is used to test if $t
is in $f
with [ "${f%$t*}" != "$f" ]
which will evaluate to true if the $f
string contains "Suzi*
" and false if not.
If the test returns true, construct the desired string using Remove Smallest Suffix Pattern ${f%$t*}
"I love
" and Remove Smallest Prefix Pattern ${f#*$t}
"and Marry
", with the 2nd string $s
"Sara
" in between.
I know this is old but since no one mentioned about using awk:
firstString="I love Suzi and Marry"
echo $firstString | awk '{gsub("Suzi","Sara"); print}'
This can be done entirely with bash string manipulation:
first="I love Suzy and Mary"
second="Sara"
first=${first/Suzy/$second}
That will replace only the first occurrence; to replace them all, double the first slash:
first="Suzy, Suzy, Suzy"
second="Sara"
first=${first//Suzy/$second}
# first is now "Sara, Sara, Sara"
If tomorrow you decide you don't love Marry either she can be replaced as well:
today=$(</tmp/lovers.txt)
tomorrow="${today//Suzi/Sara}"
echo "${tomorrow//Marry/Jesica}" > /tmp/lovers.txt
There must be 50 ways to leave your lover.
Since I can't add a comment. @ruaka To make the example more readable write it like this
full_string="I love Suzy and Mary"
search_string="Suzy"
replace_string="Sara"
my_string=${full_string/$search_string/$replace_string}
or
my_string=${full_string/Suzy/Sarah}
It's better to use bash than sed
if strings have RegExp characters.
echo ${first_string/Suzi/$second_string}
It's portable to Windows and works with at least as old as Bash 3.1.
To show you don't need to worry much about escaping let's turn this:
/home/name/foo/bar
Into this:
~/foo/bar
But only if /home/name
is in the beginning. We don't need sed
!
Given that bash gives us magic variables $PWD
and $HOME
, we can:
echo "${PWD/#$HOME/\~}"
EDIT: Thanks for Mark Haferkamp in the comments for the note on quoting/escaping ~
.*
Note how the variable $HOME
contains slashes but this didn't break anything.
Further reading: Advanced Bash-Scripting Guide.
If using sed
is a must, be sure to escape every character.
try this:
sed "s/Suzi/$secondString/g" <<<"$firstString"
Source: Stackoverflow.com