How to remove a certain symbol for a bash script

Question

I have a bash script where I get the disk usage, for example 60%. How can I remove the % symbol? Using grep or awk?

score 12 · Answer 1 · answered Aug 23 '11 at 16:00

There is no need for external tools like tror even sed as bash can do it on its own since forever.

percentage="60%"
number=${percentage%\%}

This statement removes the shortest matching substring (in this case an escaped %) from the end of the variable. There are other string manipulating facilities built into bash. It even supports regular expressions. Generally, most of the stuff you normally see people using tr, sed, awk or grep for can be done using a bash builtin. It's just almost noody knows about that and brings the big guns...

See http://tldp.org/LDP/abs/html/parameter-substitution.html#PSOREX1 for more information.

score 6 · Accepted Answer · answered Aug 23 '11 at 13:23

6

This should do it:

sed 's/%//'

Pipe your string through it for the best results.

answered Aug 23 '11 at 13:23

womble

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There's a "g" missing because otherwise it would only match the first % in each line. So make it 's/%//g'. – joechip Aug 23 '11 at 17:14
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@joechip: If there's only one `%`, as per the question, you don't need `g`. – womble Aug 23 '11 at 22:10

score 6 · Answer 3 · answered Aug 23 '11 at 14:14

6

Instead of sed, use tr.

tr -d '%'

answered Aug 23 '11 at 14:14

JCallicoat

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Good point (+1). `tr` is faster than `sed`. – Michał Šrajer Oct 03 '11 at 13:59

score 4 · Answer 4 · answered Aug 23 '11 at 13:25

4

sed is one of the easiest ways

sed -i 's/\%//g' fileName

answered Aug 23 '11 at 13:25

Mike

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score 2 · Answer 5 · answered Aug 23 '11 at 15:56

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If the disk usage is in a variable, bash can do the removal as part of a variable substitution:

diskusagepct="60%"
echo "disk usage: ${diskusagepct%\%} percent"  # prints disk usage: 60 percent
diskusagenum="${diskusagepct%\%}"  # sets diskusagenum to 60

answered Aug 23 '11 at 15:56

Gordon Davisson

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How to remove a certain symbol for a bash script

5 Answers5