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tcprks avatar Ubuntu

How to remove specific character from file

za flag
tcprks

I have a file like this.

[Guest]
[AAD_987d7f2f57d2]
[mhope]
[SABatchJobs]
[svc-ata]
[svc-bexec]
[svc-netapp]
[dgalanos]
[roleary]
[smorgan]

How to remove the '[' and ']' from the file so i can get the output as below

Guest
AAD_987d7f2f57d2
mhope
SABatchJobs
svc-ata
svc-bexec
svc-netapp
dgalanos
roleary
smorgan
38
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Score:2
pLumo avatar Ubuntu
in flag
pLumo

Use sed:

sed 's/[][]//g' file
  • The sed command is s/pattern/replacement/modifiers, meaning substitute pattern with replacement. g modifier means globally, otherwise only the first match will be replaced.
  • [...] is a character class, so any character inside the brackets match.
  • ] closes the character class unless its at first place inside. As we want to include that in our character class, we place it first.
  • Replacement is empty in our case.
  • Use sed -i '...' to edit your file in place.

You can also use grep -P like I already suggested in your other question:

grep -Po '\[\K[^]]*' file
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Lorenz Keel avatar
gr flag
Lorenz Keel
I was ready to suggest `sed 's/\[\(.*\)\]/\1/' file`, but your answer is more readable and elegant than mine :-)
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Lorenz Keel avatar
gr flag
Lorenz Keel
@tcprks if you are interested in applying the modification directly on the file (i.e. overwriting it), you can add a `-i` before `file` (this is true only for the `sed` part of the solution.
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pLumo avatar
in flag
pLumo
thanks, added that suggestion to my notes :-)
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Score:2
avatar Ubuntu
hr flag
steeldriver

The 'standard' utility to remove specific characters is tr:

NAME
       tr - translate or delete characters

SYNOPSIS
       tr [OPTION]... SET1 [SET2]

DESCRIPTION
       Translate, squeeze, and/or delete characters from standard input, writ‐
       ing to standard output.

So for example

tr -d '][' < file

Unlike GNU sed, tr only reads from and writes to standard streams; however you can simulate "in place" editing using a temporary file:

tmpfile=$(mktemp)
tr -d '][' < file > "$tmpfile" && mv "$tmpfile" file

or with the sponge command from package moreutils:

tr -d '][' < file | sponge file

You could also use awk - for example by splitting lines of the file into fields separated by ] and [ and printing only the second:

awk -F '[][]' '{print $2}' file

You can use the same tmpfile trick to simulate "in place" editing, or with GNU awk (aka gawk), use the inplace module:

gawk -i inplace -F '[][]' '{print $2}' file
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